Google Colab/IPython cell output conflicts on logfire import

TL;DR

We have previously run some python scripts via Google Colab notebooks, usually using the shell command !uv run my\_script.py. Logfire configures properly within the script and the script itself executes perfectly.

Steps

1. We have previously run some python scripts via Google Colab notebooks, usually using the shell command !uv run my_script.py . After instrumenting the codebase with logfire, there is some unexpected behavior blocking cell output.

1. Logfire configures properly within the script and the script itself executes perfectly. Spans and instrumented functions, auto-instrumented objects, etc are all properly logged and sent to the dashboard. However, the cell output shows Logfire Project URL: ____ (blank) in the output, rendered as expecting input but no change...

1. If importing logfire in a Colab/IPython notebook blocks cell output (showing a blank 'Logfire Project URL' prompt), check for a duplicate logfire.configure() call, e.g. one hiding in an init.py that runs alongside your own. That was the reporter's root cause. Setting logfire.configure(console=False) suppresses the project URL printout.

When to use

You are seeing this: Issue pydantic/logfire#1267 (closed, 14 comments): ### Description Use this skill when you run into "Google Colab/IPython cell output conflicts on logfire import".

When not to use

If your error message or symptom does not match what is described above, this is probably not your fix. Search for your exact error text instead of forcing this one to fit.

Versions

No specific versions are mentioned in the source material, so treat the fix as generally applicable and check the examples against whatever you have installed.

Why this happens

The original report does not dig into a root cause. It documents the symptom and the fix that resolved it.

Sources

• https://github.com/pydantic/logfire/issues/1267