adk migrate session` fails with greenlet_spawn error when using async driver URLs

[veevortexiq]

adk migrate session fails with greenlet_spawn error when using async driver URLs

Description

The adk migrate session command fails when using async driver URLs like postgresql+asyncpg://. The migration implementation uses synchronous SQLAlchemy but doesn't validate driver compatibility.

Environment

• ADK Version: 1.22.1
• Database: PostgreSQL
• Python: 3.12
• Drivers: asyncpg, psycopg2-binary

Steps to Reproduce

adk migrate session \
  --source_db_url "postgresql+asyncpg://postgres:pass@localhost:5432/source" \
  --dest_db_url "postgresql+asyncpg://postgres:pass@localhost:5432/dest" \
  --log_level info

Error Output

2026-01-16 10:43:27,300 - INFO - migrate_from_sqlalchemy_pickle.py:168 - Connecting to source database
2026-01-16 10:43:27,323 - INFO - migrate_from_sqlalchemy_pickle.py:176 - Connecting to destination database
2026-01-16 10:43:27,324 - ERROR - migrate_from_sqlalchemy_pickle.py:182 - Failed to connect to destination database: 
greenlet_spawn has not been called; can't call await_only() here. 
Was IO attempted in an unexpected place?

Root Cause

Files affected:

google/adk/sessions/migration/migrate_from_sqlalchemy_pickle.py (lines 168, 182)

google/adk/sessions/migration/migration_runner.py (calls the above)

The migration uses create_engine() (synchronous) but doesn't reject async driver URLs:

# Line 168
source_engine = create_engine(source_db_url)  # Synchronous

# Line 182  
dest_engine = create_engine(dest_db_url)      # Synchronous - fails with async URLs

Expected Behavior

Either support async drivers OR show clear error: "Migration requires synchronous drivers. Use postgresql:// not postgresql+asyncpg://"

Impact

Affects all users migrating v0 → v1 schema with PostgreSQL. Creates documentation mismatch since ADK 1.22.1 requires async drivers for runtime but the migration tool requires synchronous drivers.

[wuliang229]

Thanks for filing the issue. I can confirm that this issue exists and your proposed fix is good. Meanwhile, please use the synchronous driver to bypass the restriction as a temporary solution.