ADK crashes with MySQL session in v1.17.0

[hung12ct]

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Describe the bug
adk crashes with TypeError: 'tuple' object cannot be interpreted as an integer when using MySQL backend in v1.17.0.

To Reproduce
Please share a minimal code and data to reproduce your problem.
Steps to reproduce the behavior:

1. Install google-adk==1.17.0
2. Configure DatabaseSessionService with MySQL
3. Create and store a session with events
4. Error occurs during session serialization

Expected behavior
Sessions should be stored and retrieved successfully from MySQL without errors.

Screenshots
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Desktop (please complete the following information):

• OS: [e.g. macOS, Linux, Windows]
• Python version(python -V):
• ADK version(pip show google-adk):

Model Information:

• Are you using LiteLLM: Yes/No
• Which model is being used(e.g. gemini-2.5-pro)

Additional context
Add any other context about the problem here.

[zakahan]

I also encountered this problem, and I solved it by downgrading the version (I don't know exactly which version caused it, nor did I test it; in short, version 1.10 is definitely fine).

The reason for this error is probably as follows:
Omitting a lot of processing before and after, in short, during the message transmission process (when google-adk==1.17.0), the Event will be converted to bytes, and an attempt is made to execute bytes(Event). However, for Event type data, there is a place where it becomes a tuple during iteration, and a tuple cannot be converted to bytes, hence this error.

It can be reproduced this bug with this code:

from google.adk.events.event import Event
from google.adk.events.event_actions import EventActions
from google.genai.types import Content, Part
x = Event(content=Content(
  parts=[
    Part(
      text="some text"
    ),
  ],
  role='user'
), author='user',
)
print(bytes(x))

[growmuye]

same error

......
  File "/Users/gmy/Documents/liepinProjects/ins-pydora-internal/.venv/lib/python3.12/site-packages/sqlalchemy/engine/default.py", line 1521, in _init_compiled
    flattened_processors[key](compiled_params[key])
  File "/Users/gmy/Documents/liepinProjects/ins-pydora-internal/.venv/lib/python3.12/site-packages/sqlalchemy/sql/type_api.py", line 2096, in process
    return fixed_impl_processor(
           ^^^^^^^^^^^^^^^^^^^^^
  File "/Users/gmy/Documents/liepinProjects/ins-pydora-internal/.venv/lib/python3.12/site-packages/sqlalchemy/sql/sqltypes.py", line 914, in process
    return DBAPIBinary(value)
           ^^^^^^^^^^^^^^^^^^
  File "/Users/gmy/Documents/liepinProjects/ins-pydora-internal/.venv/lib/python3.12/site-packages/pymysql/__init__.py", line 129, in Binary
    return bytes(x)
           ^^^^^^^^
sqlalchemy.exc.StatementError: (builtins.TypeError) 'tuple' object cannot be interpreted as an integer

我移除这段代码后，就可以使用了，或许应该处理这个？ @hung12ct

[hung12ct]

Hi @growmuye , I’ve raised a PR: #3282 to fix this issue. I’m still using v1.16 until it’s fixed.