GitVersion output is not valid JSON

[kgsosa]

Hello, I just wanted to ask if someone out there had an experience on how to fix the error "GitVersion output is not valid JSON." This is happening when merging the main into a feature branch. Below is my config in YAML

error

Command: git -C D:\a\1\s rev-parse --is-shallow-repository
Command: C:\hostedtoolcache\windows\GitVersion.Tool\6.3.0\dotnet-gitversion.exe --roll-forward Major D:\a\1\s /output json /l console
##[error]GitVersion output is not valid JSON
dotnet-gitversion Output:
-------------------
undefined
-------------------
undefined

In the pipeline

steps:
  - checkout: self
    fetchDepth: 0

  - task: gitversion/setup@3
    displayName: Setup GitVersion
    inputs:
      versionSpec: '6.3.x'

  - task: gitversion/execute@3
    displayName: Determine Version
    inputs:
      configFilePath: './GitVersion.yaml'

GitVersion yaml

next-version: 2025.3.0
workflow: TrunkBased/preview1

branches:
  main:
    regex: ^master$|^main$
    increment: Patch 

  feature:
    regex: ^feature(s)?/.*
    increment: Minor 

  fix:
    regex: ^(fix(es)?|bugfix(es)?)/.*
    increment: Patch 

Is there something I need to change in a config, or is there something wrong with my GitVersion yaml?

[joaopbnogueira]

In my experience this is some sort of issue with your yaml. Is this the full yaml?

[kgsosa]

What you're seeing is my full YAML.

[joaopbnogueira]

did you try some bissection work? i.e. starting with the most simple configuration:

next-version: 2025.3.0
workflow: TrunkBased/preview1

and moving on step by step

[kgsosa]

I can try that on, but the issue is only appearing when a PR was approved and the most recent commit for the PR was merged from main.

[KjellOlav]

I had the same error, invalid json. In my case I was missing the regex on each branch and it seemed like the next version calculator failed silently and produced an invalid json. I would suggest to test your regex and make sure they work for your branches.

[joaopbnogueira]

Also had a similar issue and in my case i was using an invalid variable on a label definition, but with such a small yaml most of the configurations likely come from the default template... A sexta, 6/06/2025, 10:59, Kjell Olav Håland ***@***.***> escreveu:

…

I had the same error, invalid json. In my case I was missing the regex on each branch and it seemed like the next version calculator failed silently and produced an invalid json. I would suggest to test your regex and make sure they work for your branches. — Reply to this email directly, view it on GitHub <#4558 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AAMPWJVW3HIZ4JIH25TYFEL3CFJ6XAVCNFSM6AAAAAB6CUWG5SVHI2DSMVQWIX3LMV43URDJONRXK43TNFXW4Q3PNVWWK3TUHMYTGMZYG44TMNA> . You are receiving this because you commented.Message ID: ***@***.***>

[9swampy]

Ditto on the invalid yaml. v6 has really shaken things up and I have been really struggling to get:

1. A valid configuration that even works
2. A configuration that does what I expect gitversion to do.

To be fair i've found configuration a little trial and error in previous versions so I compromised when I had a config that was fit for purpose but 6 seems to be a completely different beast.

As others have suggested I'd try starting from a clean standard config and build back up to where you want to get. That's where I am too :)