Firebase functions work intermittently due to the error: 'Failed to load function definition from source: FirebaseError: User code failed to load.'

[mustafaekim]

Hi,

When I run the command firebase serve -o 0.0.0.0 it sometimes work, sometimes does not. serve-fails.txt

Similarly, when I run the command firebase emulators:start --only "functions,hosting emulate-fails.txt

The error does not say much:"!! functions: Failed to load function definition from source: FirebaseError: User code failed to load. Cannot determine backend specification"

I can assure you I do nothing between running the commands. Even if it works at a time, it may not the second time.

The error is very annoying, unpredictable and breaks our whole deployment. It can fail over and over multiple times and hence we cannot update our product.

• Does anyfile inside the "functions/lib" folder change after running the above commands?
• Do these commands have side-effects?
• Why the "--debug" mode does not reveal any more information and how can I find more information?

My environment: nodejs: 18.16.1 firebase-tools: 13.1.0 windows: Windows 11 Home Single Language; version=22H2

[google-oss-bot]

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[johndunderhill]

There were a lot of people suffering with this. People have been tearing their development environments apart, re-installing things, and tweaking things, only to have the problem recur. I suspect some do not re-post when the problem returns. See #5888 and others.

We ran into this in a monorepo with larger function files. No rhyme or reason to it in our case.

I most cases, I believe this is just a timeout error, due to the 10-second timeout when loading (importing) user code in the emulator. We made a patch based on this PR and have not seen the problem since. Unfortunately the PR has become stale.

If I understand correctly, this could also be caused if the emulator runs into problems loading your code, although you might get an additional error in that case. In any case, @taeold has a very clear description here on how to make sure that's not the issue.

[mustafaekim]

Thank you for sharing the issue link. However, it appears that there hasn't been much action taken on it. I'm puzzled by how only a few seem to be affected by this. That is a serious threat to our development and keeping our product up-to-date effort because it is unpredictable and sometimes it causes a lot of delays into our deployments. Last month, it did not work for the whole day!