Flutter Driver Isolate Connection Error After App Reinstall on iOS

[dikshant-dwivedi-lic]

Flutter Driver Isolate Connection Error After App Reinstall on iOS

Problem Description

When running Flutter driver tests on iOS after performing app uninstall/install operations (fresh install simulation), the Flutter driver fails to establish proper isolate connection, resulting in Cannot read properties of undefined (reading 'isError') error.

Steps to Reproduce

1. Uninstall the app using mobile: removeApp command
2. Install the app using installApp command
3. Launch the app using mobile: launchApp command
4. Switch to Flutter context and attempt to run Flutter driver commands
5. Execute any Flutter driver command (e.g., flutter:waitFor)

Expected Behavior

Flutter driver should successfully connect to the app's isolate and execute commands without errors.

Actual Behavior

Flutter driver fails with isolate connection error:

2025-08-11T11:30:18.877Z WARN @wdio/appium-service: 2025-08-11 17:00:18:876 - [b36f2864][FlutterDriver@b562] Error: {}
at IsolateSocket.socket.call (/Users/kishantalekar/.appium/node_modules/appium-flutter-driver/lib/sessions/observatory.ts:68:39)
at processTicksAndRejections (node:internal/process/task_queues:105:5)

WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"

Environment

• Platform: iOS Simulator
• Device: iPhone 16 Pro, iOS 18.3
• Appium: v2.19.0
• Flutter Driver: appium-flutter-driver@2.18.1

---

Full Test Log

> test:onboardingSkipFlow
> wdio run ./wdio.conf.js --spec=./test/specs/core/onboardingSkipFlow.test.js

Execution of 1 workers started at 2025-08-11T11:28:25.566Z

(node:86566) [MODULE_TYPELESS_PACKAGE_JSON] Warning: Module type of file:///Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/wdio.conf.js is not specified and it doesn't parse as CommonJS.
Reparsing as ES module because module syntax was detected. This incurs a performance overhead.
To eliminate this warning, add "type": "module" to /Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/package.json.
(Use `node --trace-warnings ...` to show where the warning was created)
2025-08-11T11:28:25.582Z INFO @wdio/cli:launcher: Run onPrepare hook
2025-08-11T11:28:25.588Z INFO @wdio/appium-service: Will spawn Appium process: appium --base-path / --relaxed-security --allow-cors --allow-insecure ["chromedriver_autodownload"] --deny-insecure [] --session-override --debug-log-spacing --log-timestamp --local-timezone --port 63484
2025-08-11T11:28:39.937Z INFO @wdio/appium-service: Appium started with ID: 86599
2025-08-11T11:28:39.937Z INFO @wdio/appium-service: Appium logs written to stdout
2025-08-11T11:28:39.938Z INFO @wdio/cli:launcher: Run onWorkerStart hook
2025-08-11T11:28:39.938Z INFO @wdio/local-runner: Start worker 0-0 with arg: run ./wdio.conf.js --spec=./test/specs/core/onboardingSkipFlow.test.js
[0-0] 2025-08-11T11:28:40.923Z INFO @wdio/local-runner: Run worker command: run
[0-0] (node:86621) [MODULE_TYPELESS_PACKAGE_JSON] Warning: Module type of file:///Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/wdio.conf.js is not specified and it doesn't parse as CommonJS.
[0-0] Reparsing as ES module because module syntax was detected. This incurs a performance overhead.
[0-0] To eliminate this warning, add "type": "module" to /Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/package.json.
[0-0] (Use `node --trace-warnings ...` to show where the warning was created)
[0-0] 🚀 Starting test session...
[0-0] RUNNING in iOS - file:///test/specs/core/onboardingSkipFlow.test.js
[0-0] 2025-08-11T11:28:41.268Z INFO webdriver: Initiate new session using the WebDriver protocol
[0-0] 2025-08-11T11:28:41.269Z INFO @wdio/utils: Connecting to existing driver at http://127.0.0.1:63484/
[0-0] 2025-08-11T11:28:41.282Z INFO webdriver: [POST] http://127.0.0.1:63484/session
[0-0] 2025-08-11T11:29:03.314Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:29:03.315Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:29:03.315Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:29:14.988Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:29:14.990Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:29:14.990Z INFO webdriver: COMMAND switchAppiumContext("NATIVE_APP")
[0-0] 2025-08-11T11:29:14.991Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:29:14.991Z INFO webdriver: DATA { name: 'NATIVE_APP' }
[0-0] 2025-08-11T11:29:15.002Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:29:15.003Z INFO webdriver: COMMAND executeScript("mobile: removeApp", <object>)
[0-0] 2025-08-11T11:29:15.004Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:29:15.004Z INFO webdriver: DATA {
[0-0] script: 'mobile: removeApp',
[0-0] args: [ { bundleId: 'nz.co.mobile.app.xyz.dev' } ]
[0-0] }
[0-0] 2025-08-11T11:29:15.458Z INFO webdriver: RESULT true
[0-0] 2025-08-11T11:29:16.461Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:29:16.461Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:29:16.462Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:29:26.042Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:29:26.043Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:29:26.043Z INFO webdriver: COMMAND switchAppiumContext("NATIVE_APP")
[0-0] 2025-08-11T11:29:26.044Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:29:26.044Z INFO webdriver: DATA { name: 'NATIVE_APP' }
[0-0] 2025-08-11T11:29:26.052Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:29:26.055Z INFO webdriver: COMMAND installApp("/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/build/ios/iphonesimulator/Runner.app")
[0-0] 2025-08-11T11:29:26.055Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/appium/device/install_app
[0-0] 2025-08-11T11:29:26.055Z INFO webdriver: DATA {
[0-0] appPath: '/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/build/ios/iphonesimulator/Runner.app'
[0-0] }
[0-0] 2025-08-11T11:29:28.151Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:29:28.151Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:29:28.151Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:29:28.152Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:29:37.736Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:29:37.738Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:29:37.738Z INFO webdriver: COMMAND switchAppiumContext("FLUTTER")
[0-0] 2025-08-11T11:29:37.740Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:29:37.740Z INFO webdriver: DATA { name: 'FLUTTER' }
[0-0] 2025-08-11T11:29:37.753Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:29:39.755Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:29:39.755Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:29:39.756Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:29:50.198Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:29:50.201Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:29:50.201Z INFO webdriver: COMMAND switchAppiumContext("NATIVE_APP")
[0-0] 2025-08-11T11:29:50.203Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:29:50.203Z INFO webdriver: DATA { name: 'NATIVE_APP' }
[0-0] 2025-08-11T11:29:50.211Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:29:50.215Z INFO webdriver: COMMAND executeScript("mobile: launchApp", <object>)
[0-0] 2025-08-11T11:29:50.217Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:29:50.217Z INFO webdriver: DATA {
[0-0] script: 'mobile: launchApp',
[0-0] args: [ { bundleId: 'nz.co.mobile.app.xyz.dev' } ]
[0-0] }
[0-0] 2025-08-11T11:29:54.629Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:29:54.631Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:29:54.631Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:29:54.635Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:30:04.228Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:30:04.229Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:30:04.229Z INFO webdriver: COMMAND switchAppiumContext("FLUTTER")
[0-0] 2025-08-11T11:30:04.230Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:30:04.231Z INFO webdriver: DATA { name: 'FLUTTER' }
[0-0] 2025-08-11T11:30:04.239Z INFO webdriver: RESULT null
[0-0] 🧪 Starting test: should skip onboarding and handle notification prompt with warm/cold restarts
[0-0] 2025-08-11T11:30:09.266Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:30:09.266Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:30:09.267Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:30:18.849Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:30:18.849Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:30:18.849Z INFO webdriver: COMMAND switchAppiumContext("FLUTTER")
[0-0] 2025-08-11T11:30:18.850Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:30:18.850Z INFO webdriver: DATA { name: 'FLUTTER' }
[0-0] 2025-08-11T11:30:18.855Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:30:18.857Z INFO webdriver: COMMAND executeScript("flutter:waitFor", <object>)
[0-0] 2025-08-11T11:30:18.857Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:30:18.857Z INFO webdriver: DATA {
[0-0] script: 'flutter:waitFor',
[0-0] args: [
[0-0] 'eyJmaW5kZXJUeXBlIjoiQnlWYWx1ZUtleSIsImtleVZhbHVlU3RyaW5nIjoib25ib2FyZGluZ19sb2dvIiwia2V5VmFsdWVUeXBlIjoiU3RyaW5nIn0',
[0-0] 5000
[0-0] ]
[0-0] }
2025-08-11T11:30:18.877Z WARN @wdio/appium-service: 2025-08-11 17:00:18:876 - [b36f2864][FlutterDriver@b562] Error: {}
at IsolateSocket.socket.call (/Users/kishantalekar/.appium/node_modules/appium-flutter-driver/lib/sessions/observatory.ts:68:39)
at processTicksAndRejections (node:internal/process/task_queues:105:5)

[0-0] 2025-08-11T11:30:18.909Z WARN webdriver: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] 2025-08-11T11:30:18.909Z INFO webdriver: Retrying 1/2
[0-0] 2025-08-11T11:30:18.909Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:30:18.909Z INFO webdriver: DATA {
[0-0] script: 'flutter:waitFor',
[0-0] args: [
[0-0] 'eyJmaW5kZXJUeXBlIjoiQnlWYWx1ZUtleSIsImtleVZhbHVlU3RyaW5nIjoib25ib2FyZGluZ19sb2dvIiwia2V5VmFsdWVUeXBlIjoiU3RyaW5nIn0',
[0-0] 5000
[0-0] ]
[0-0] }
2025-08-11T11:30:18.911Z WARN @wdio/appium-service: 2025-08-11 17:00:18:911 - [b36f2864][FlutterDriver@b562] Error: {}
at IsolateSocket.socket.call (/Users/kishantalekar/.appium/node_modules/appium-flutter-driver/lib/sessions/observatory.ts:68:39)
at processTicksAndRejections (node:internal/process/task_queues:105:5)

[0-0] 2025-08-11T11:30:19.414Z WARN webdriver: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] 2025-08-11T11:30:19.414Z INFO webdriver: Retrying 2/2
[0-0] 2025-08-11T11:30:19.415Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:30:19.415Z INFO webdriver: DATA {
[0-0] script: 'flutter:waitFor',
[0-0] args: [
[0-0] 'eyJmaW5kZXJUeXBlIjoiQnlWYWx1ZUtleSIsImtleVZhbHVlU3RyaW5nIjoib25ib2FyZGluZ19sb2dvIiwia2V5VmFsdWVUeXBlIjoiU3RyaW5nIn0',
[0-0] 5000
[0-0] ]
[0-0] }
2025-08-11T11:30:19.421Z WARN @wdio/appium-service: 2025-08-11 17:00:19:420 - [b36f2864][FlutterDriver@b562] Error: {}
at IsolateSocket.socket.call (/Users/kishantalekar/.appium/node_modules/appium-flutter-driver/lib/sessions/observatory.ts:68:39)
at processTicksAndRejections (node:internal/process/task_queues:105:5)

[0-0] 2025-08-11T11:30:19.423Z ERROR webdriver: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] [ERROR] [DriverHelpers] waitFor failed: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor" null {}
[0-0] [ERROR] [onboardingPage] ❌ Failed to find welcome overlay elements: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor" null {}
[0-0] [ERROR] [AssertionHelper] Welcome overlay visibility assertion failed: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor" {}
[0-0] [ERROR] Failed to capture screenshot: directory (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/screenshots) doesn't exist {}
[0-0] ❌ Test failed: should skip onboarding and handle notification prompt with warm/cold restarts - WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] 🧪 Starting test: should skip onboarding and handle notification prompt with warm/cold restarts
[0-0] 2025-08-11T11:30:21.457Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:30:21.457Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:30:21.458Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:30:31.048Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:30:31.049Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:30:31.050Z INFO webdriver: COMMAND switchAppiumContext("FLUTTER")
[0-0] 2025-08-11T11:30:31.051Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:30:31.051Z INFO webdriver: DATA { name: 'FLUTTER' }
[0-0] 2025-08-11T11:30:31.057Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:30:31.058Z INFO webdriver: COMMAND executeScript("flutter:waitFor", <object>)
[0-0] 2025-08-11T11:30:31.058Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:30:31.058Z INFO webdriver: DATA {
[0-0] script: 'flutter:waitFor',
[0-0] args: [
[0-0] 'eyJmaW5kZXJUeXBlIjoiQnlWYWx1ZUtleSIsImtleVZhbHVlU3RyaW5nIjoib25ib2FyZGluZ19sb2dvIiwia2V5VmFsdWVUeXBlIjoiU3RyaW5nIn0',
[0-0] 5000
[0-0] ]
[0-0] }
2025-08-11T11:30:31.063Z WARN @wdio/appium-service: 2025-08-11 17:00:31:063 - [b36f2864][FlutterDriver@b562] Error: {}
at IsolateSocket.socket.call (/Users/kishantalekar/.appium/node_modules/appium-flutter-driver/lib/sessions/observatory.ts:68:39)
at processTicksAndRejections (node:internal/process/task_queues:105:5)

[0-0] 2025-08-11T11:30:31.067Z WARN webdriver: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] 2025-08-11T11:30:31.067Z INFO webdriver: Retrying 1/2
[0-0] 2025-08-11T11:30:31.067Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:30:31.067Z INFO webdriver: DATA {
[0-0] script: 'flutter:waitFor',
[0-0] args: [
[0-0] 'eyJmaW5kZXJUeXBlIjoiQnlWYWx1ZUtleSIsImtleVZhbHVlU3RyaW5nIjoib25ib2FyZGluZ19sb2dvIiwia2V5VmFsdWVUeXBlIjoiU3RyaW5nIn0',
[0-0] 5000
[0-0] ]
[0-0] }
2025-08-11T11:30:31.069Z WARN @wdio/appium-service: 2025-08-11 17:00:31:069 - [b36f2864][FlutterDriver@b562] Error: {}
at IsolateSocket.socket.call (/Users/kishantalekar/.appium/node_modules/appium-flutter-driver/lib/sessions/observatory.ts:68:39)
at processTicksAndRejections (node:internal/process/task_queues:105:5)

[0-0] 2025-08-11T11:30:31.571Z WARN webdriver: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] 2025-08-11T11:30:31.572Z INFO webdriver: Retrying 2/2
[0-0] 2025-08-11T11:30:31.572Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:30:31.572Z INFO webdriver: DATA {
[0-0] script: 'flutter:waitFor',
[0-0] args: [
[0-0] 'eyJmaW5kZXJUeXBlIjoiQnlWYWx1ZUtleSIsImtleVZhbHVlU3RyaW5nIjoib25ib2FyZGluZ19sb2dvIiwia2V5VmFsdWVUeXBlIjoiU3RyaW5nIn0',
[0-0] 5000
[0-0] ]
[0-0] }
2025-08-11T11:30:31.578Z WARN @wdio/appium-service: 2025-08-11 17:00:31:578 - [b36f2864][FlutterDriver@b562] Error: {}
at IsolateSocket.socket.call (/Users/kishantalekar/.appium/node_modules/appium-flutter-driver/lib/sessions/observatory.ts:68:39)
at processTicksAndRejections (node:internal/process/task_queues:105:5)

[0-0] 2025-08-11T11:30:31.584Z ERROR webdriver: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] [ERROR] [DriverHelpers] waitFor failed: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor" null {}
[0-0] [ERROR] [onboardingPage] ❌ Failed to find welcome overlay elements: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor" null {}
[0-0] [ERROR] [AssertionHelper] Welcome overlay visibility assertion failed: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor" {}
[0-0] [ERROR] Failed to capture screenshot: directory (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/screenshots) doesn't exist {}
[0-0] ❌ Test failed: should skip onboarding and handle notification prompt with warm/cold restarts - WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[0-0] unknown error in "⏩ Onboarding Skip Flow - Quick User Journey.📱 Skip Onboarding Journey with App State Testing.should skip onboarding and handle notification prompt with warm/cold restarts"
unknown error: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
at async DriverHelpers.waitFor (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/helpers/driver.helper.js:75:7)
at async OnboardingPage.waitForWelcomeOverlay (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/pages/onboarding.page.js:115:7)
at async AssertionsHelper.assertWelcomeOverlayVisible (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/helpers/assertions.helper.js:29:7)
at async Context.<anonymous> (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/specs/core/onboardingSkipFlow.test.js:56:7)
[0-0] [INFO] [OnboardingSkipFlow] 🧹 Cleaning up Onboarding Skip Flow Test Suite {}
[0-0] 2025-08-11T11:30:31.590Z INFO webdriver: The standard Appium `contexts` method is used. If you want to get more detailed data, you can set `returnDetailedContexts` to `true`.
[0-0] 2025-08-11T11:30:31.590Z INFO webdriver: COMMAND getAppiumContexts()
[0-0] 2025-08-11T11:30:31.590Z INFO webdriver: [GET] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/contexts
[0-0] 2025-08-11T11:30:41.159Z INFO webdriver: RESULT [ 'NATIVE_APP', 'FLUTTER' ]
[0-0] 2025-08-11T11:30:41.161Z INFO webdriver: The standard Appium `context`-method is used. If you want to switch to a webview with a specific title or url, please provide an object with the `title` or `url` property. See https://webdriver.io/docs/api/mobile/switchContext for more information.
[0-0] 2025-08-11T11:30:41.161Z INFO webdriver: COMMAND switchAppiumContext("NATIVE_APP")
[0-0] 2025-08-11T11:30:41.161Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/context
[0-0] 2025-08-11T11:30:41.161Z INFO webdriver: DATA { name: 'NATIVE_APP' }
[0-0] 2025-08-11T11:30:41.166Z INFO webdriver: RESULT null
[0-0] 2025-08-11T11:30:41.166Z INFO webdriver: COMMAND executeScript("mobile: removeApp", <object>)
[0-0] 2025-08-11T11:30:41.166Z INFO webdriver: [POST] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0/execute/sync
[0-0] 2025-08-11T11:30:41.166Z INFO webdriver: DATA {
[0-0] script: 'mobile: removeApp',
[0-0] args: [ { bundleId: 'nz.co.mobile.app.xyz.dev' } ]
[0-0] }
[0-0] 2025-08-11T11:30:41.720Z INFO webdriver: RESULT true
[0-0] 2025-08-11T11:30:41.728Z INFO webdriver: COMMAND deleteSession()
[0-0] 2025-08-11T11:30:41.729Z INFO webdriver: [DELETE] http://127.0.0.1:63484/session/b36f2864-09ef-401e-ae22-73e8accde8e0
2025-08-11T11:30:41.900Z WARN @wdio/appium-service: 2025-08-11 17:00:41:900 - [cf5c1714][Xcode] xcodebuild exited with code 'null' and signal 'SIGTERM'

[0-0] 2025-08-11T11:30:42.094Z INFO webdriver: RESULT null
[0-0] 🏁 Test session completed
[0-0] 2025-08-11T11:30:42.199Z INFO @wdio/local-runner: Received SIGINT, giving process 5000ms to shutdown gracefully
[0-0] FAILED in iOS - file:///test/specs/core/onboardingSkipFlow.test.js
2025-08-11T11:30:42.228Z INFO @wdio/cli:launcher: Run onWorkerEnd hook

## "spec" Reporter:

[Runner.app iOS #0-0] Running: Runner.app on iOS
[Runner.app iOS #0-0] Session ID: b36f2864-09ef-401e-ae22-73e8accde8e0
[Runner.app iOS #0-0]
[Runner.app iOS #0-0] » test/specs/core/onboardingSkipFlow.test.js
[Runner.app iOS #0-0] ⏩ Onboarding Skip Flow - Quick User Journey
[Runner.app iOS #0-0] 📱 Skip Onboarding Journey with App State Testing
[Runner.app iOS #0-0] ✖ should skip onboarding and handle notification prompt with warm/cold restarts (1x retries)
[Runner.app iOS #0-0]
[Runner.app iOS #0-0] 1 failing (1m 38.7s)
[Runner.app iOS #0-0]
[Runner.app iOS #0-0] 1) 📱 Skip Onboarding Journey with App State Testing should skip onboarding and handle notification prompt with warm/cold restarts
[Runner.app iOS #0-0] WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[Runner.app iOS #0-0] unknown error: WebDriverError: An unknown server-side error occurred while processing the command. Original error: Cannot read properties of undefined (reading 'isError') when running "execute/sync" with method "POST" and args "flutter:waitFor"
[Runner.app iOS #0-0] at async DriverHelpers.waitFor (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/helpers/driver.helper.js:75:7)
[Runner.app iOS #0-0] at async OnboardingPage.waitForWelcomeOverlay (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/pages/onboarding.page.js:115:7)
[Runner.app iOS #0-0] at async AssertionsHelper.assertWelcomeOverlayVisible (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/helpers/assertions.helper.js:29:7)
[Runner.app iOS #0-0] at async Context.<anonymous> (/Users/kishantalekar/Desktop/WORK_TW/x-xyz-refactor/appium/test/specs/core/onboardingSkipFlow.test.js:56:7)

Spec Files: 0 passed, 1 failed, 1 total (100% completed) in 00:02:16

2025-08-11T11:30:42.229Z INFO @wdio/local-runner: Shutting down spawned worker
2025-08-11T11:30:42.481Z INFO @wdio/local-runner: Waiting for 0 to shut down gracefully
2025-08-11T11:30:42.481Z INFO @wdio/local-runner: shutting down
2025-08-11T11:30:42.481Z INFO @wdio/cli:launcher: Run onComplete hook
2025-08-11T11:30:42.481Z INFO @wdio/appium-service: Killing entire Appium tree
2025-08-11T11:30:42.515Z INFO @wdio/appium-service: Process and its children successfully terminated

[KazuCocoa]

Please attach the full appium server log

[dikshant-dwivedi-lic]

@KazuCocoa I’m not sure if this is exactly what’s needed. I tried enabling verbose logs, but the Appium server only shows this:

appium --log appium_server.log --log-timestamp --log-level debug 
2025-08-11 23:18:44:706 - [Appium] Welcome to Appium v2.19.0 (REV 552db40622bb7a82d9c6d67d2d6bcf3694b47e30)
2025-08-11 23:18:44:709 - [Appium] Non-default server args:
2025-08-11 23:18:44:710 - [Appium] {
  logTimestamp: true
}
2025-08-11 23:18:44:710 - [Appium] The autodetected Appium home path: /Users/dikshantdwivedi/.appium
2025-08-11 23:18:44:710 - [Appium] Attempting to load driver flutter...
2025-08-11 23:18:44:722 - [Appium] Requiring driver at /Users/dikshantdwivedi/.appium/node_modules/appium-flutter-driver/build/lib/driver.js
2025-08-11 23:18:50:509 - [Appium] FlutterDriver has been successfully loaded in 5.798s
2025-08-11 23:18:50:522 - [Appium] Appium REST http interface listener started on http://0.0.0.0:4723
2025-08-11 23:18:50:523 - [Appium] You can provide the following URLs in your client code to connect to this server:
        http://127.0.0.1:4723/ (only accessible from the same host)
        http://192.168.1.4:4723/
        http://169.254.130.60:4723/
2025-08-11 23:18:50:524 - [Appium] Available drivers:
2025-08-11 23:18:50:524 - [Appium]   - flutter@2.18.1 (automationName 'Flutter')
2025-08-11 23:18:50:524 - [Appium] No plugins have been installed. Use the "appium plugin" command to install the one(s) you want to use.

[KazuCocoa]

Your attached one means the Appium server didn't receive anything.

In the original log, the client launched the appium server as:

2025-08-11T11:28:25.588Z INFO @wdio/appium-service: Will spawn Appium process: appium --base-path / --relaxed-security --allow-cors --allow-insecure ["chromedriver_autodownload"] --deny-insecure [] --session-override --debug-log-spacing --log-timestamp --local-timezone --port 63484
2025-08-11T11:28:39.937Z INFO @wdio/appium-service: Appium started with ID: 86599

so, the NodeJS process collect output (I guess) but you also could get the appium server log with --log appium server arg for the appium-service in webdriverio.
https://appium.io/docs/en/latest/cli/args/