Briefcase run works dev doesn't: Toga application must have a formal name

[hlovatt]

Hi,

Unusual one:

HelloWorld tutorial App was working on one computer, moved to new MacBook and it stopped working with briefcase dev but still works with briefcase run (I rebuilt on new machine - didn't try run before rebuild). dev didn't work before rebuild nor after.

Error is:

Traceback (most recent call last):
  File "<string>", line 1, in <module>
  File "<frozen runpy>", line 226, in run_module
  File "<frozen runpy>", line 98, in _run_module_code
  File "<frozen runpy>", line 88, in _run_code
  File "/Users/howardlovatt/repos/beeware/helloworld/src/helloworld/__main__.py", line 4, in <module>
    main().main_loop()
    ^^^^^^
  File "/Users/howardlovatt/repos/beeware/helloworld/src/helloworld/app.py", line 52, in main
    return HelloWorld()
           ^^^^^^^^^^^^
  File "/opt/anaconda3/lib/python3.12/site-packages/toga/app.py", line 276, in __init__
    raise RuntimeError("Toga application must have a formal name")
RuntimeError: Toga application must have a formal name

Have attached log. Note toml, it does have a formal name.

Any suggestions?

briefcase.2024_12_12-13_02_56.dev.log

[freakboy3742]

That error indicates that the packaging metadata for the app itself hasn't been written out. There should be a helloworld.dist-info directory in your src folder (the same location that contains the helloworld directory); this is the "formal name" that it's trying to find at runtime (the pyproject.toml is the source of the metadata, not the location that is read at runtime).

That metadata file is written as part of installing the app code. Running briefcase update should re-create it in your built app; briefcase dev -r should re-create it in your development environment.

You say this has occurred as a result of moving the app to a new computer - how did you do this move? If the .dist-info was missing, that should have triggered re-creating the file, so I'm not entirely clear how this might have occurred.

[hlovatt]

Thanks that has fixed the problem, needed both update and dev -r.

I moved the files by copying from 1st Mac to iCloud and then from iCloud to 2nd Mac. iCloud only used as a 'dropbox', code not run from there.