WEB UI Evals is not working

[erick-saenz]

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Describe the Bug:

When I try to update an eval case in the Web UI I get this error in the logs

INFO: 127.0.0.1:49878 - "PUT /dev/apps/app/eval_sets/eval_set_3/evals/sacreation HTTP/1.1" 422 Unprocessable Entity

Steps to Reproduce:
Please provide a numbered list of steps to reproduce the behavior:

1. I run this command

uv run adk web . --host 127.0.0.1 --port 8186 --allow_origins '*' --reload_agents

2. Go to the Web UI and start a new session
3. Create a conversation with the agent
4. Go to evals tab and create a new Eval Set
5. Create a new eval case using current session
6. Edit eval case data and try to save
7. Error is reaised

Expected Behavior:
The eval case is saved succesfully and I can run the eval set to validate results

Observed Behavior:
What actually happened? Include error messages or crash stack traces here.

When I try to update an eval case in the Web UI I get this error in the logs

INFO: 127.0.0.1:49878 - "PUT /dev/apps/app/eval_sets/eval_set_3/evals/sacreation HTTP/1.1" 422 Unprocessable Entity

Environment Details:

• ADK Library Version: 2.0.0, 2.1.0, 2.2.0, 2.3.0
• Desktop OS: Linux
• Python Version (python -V): 3.12.3

Model Information:

• Are you using LiteLLM: No
• Which model is being used: gemini-2.5-flash

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Regression:
Did this work in a previous version of ADK? If so, which one?

No, It didn't. I tried from version 2.0.0 and ahead

How often has this issue occurred?:

• Always (100%)

[surajksharma07]

@erick-saenz — dug into this and it looks like a schema quirk, not something on your end.
When the eval case gets loaded into the edit dialog, an optional content field gets dropped since it's empty, then rejected as required the moment you save — which lines up exactly with that 422.

As a workaround, try adding a = None default to content on InvocationEvent in eval_case.py and restart adk web.
Could you confirm that clears it ?

[erick-saenz]

Hi @surajksharma07

I don't use any eval_case.py file. I suppose it is the schema file in ADK source code. Is that the case?

[surajksharma07]

Yes, exactly that — eval_case.py is part of the ADK library itself (google/adk/evaluation/eval_case.py), not anything in your project.
You can find it under your venv's site-packages/google/adk/evaluation/eval_case.py, or run python -c "import google.adk.evaluation.eval_case as m; print(m.file)" to get the exact path.

It's just a local patch to confirm the root cause, not something you'd need to maintain — once you add the = None default to content on InvocationEvent there and restart adk web, try the edit and save again and let me know if the 422 is gone!