`SyntaxError: source code string cannot contain null bytes` after packaging with `nicegui-pack`

[romaintailhurat]

First Check

• I added a very descriptive title here.
• This is not a Q&A. I am sure something is wrong with NiceGUI or its documentation.
• I used the GitHub search to find a similar issue and came up empty.

Description

Hi!

I wrote a very simple app in order to test the packaging of NiceGUI:

from multiprocessing import freeze_support
freeze_support()
from nicegui import ui, native  # noqa

ui.label("TEST")

ui.run(reload=False, port=native.find_open_port())

My project is managed using uv, which I used to install NiceGUI (3.0.3) and the latest version of PyInstaller (6.16.0).

My system is macOS Tahoe 26.0.1.

I packaged the app with: uv run nicegui-pack --onefile --name "psg" main.py.

I'm trying to run the app with: ./dist/psg, the app launches but it display a 500 error page with the message SyntaxError: source code string cannot contain null bytes.

I checked: my source file doesn't contains any hidden null character.

I tested the app with both Safari and Firefox, same issue.

Thanks for considering my troubles.

NiceGUI Version

3.0.3

Python Version

3.13

Browser

Safari

Operating System

macOS

Additional Context

No response

[Fleckso]

Hey, i have the same problem and couldn't solve it.
Im using:

• Windows
• Python==3.10.11
• NiceGUI==3.0.2
• Pyinstaller==6.16.0

I tried different build commands with any combination of onefile, windowed.
Will let you know if I find smth.

[Fleckso]

I solved my problem.... you have to add a page which you want to show... like this:

@ui.page('/')
def page():
    ui.link('Visit other page', other_page)
    ui.link('Visit dark page', dark_page)

https://nicegui.io/documentation/section_pages_routing

In the error message you can read this:
return await page('')
thats why i checked the NiceGui Page thing.

[romaintailhurat]

Wow indeed that also solved my problem! Thanks @Fleckso .

I'm still a bit confused, the deployment page of the website gives an example that specifically doesn't use the page construct. Should It be updated?

[evnchn]

gives an example that specifically doesn't use the page construct

@romaintailhurat You can actually do a PR to change the docs.

But it's not as simple as a markdown file though, which is honestly a good thing.

🤡

[falkoschindler]

Great news that you found a solution! 🎉

I just hesitated a little to change the documentation, because I don't quite understand why the page function is necessary now. Does anyone have an idea what is going on?

[python-and-novella]

@falkoschindler in nicegui\ui_run.py, line 128 is:

def run_script() -> None:
    runpy.run_path(sys.argv[0])

Does it cause bug after packing ?
The print(sys.argv[0]) in code will print exe's path instead of code's path.

[python-and-novella]

@falkoschindler If it is not easy to solve, I think we can treat script mode as a not-for-packaging mode, and write it in document.

[evnchn]

I think we can accept that as a partial conclusion, while being open to any PRs which enable script mode to be packed.

After all, I don't see anything which is exclusive to script mode (other than the ease of use) and we're not losing anything.