AgentCore Runtime session-id requires 33+ characters

Tried --session-id session-1 with a Memory-enabled agent and got:

Output

1 validation error detected: Value at 'runtimeSessionId' failed to satisfy
constraint: Member must have length greater than or equal to 33

Session IDs must be 33 characters or longer. Not documented in the CLI docs or --help — it's an API-level validation.

Terminal

# NG: 9 chars
agentcore invoke "Hello" --session-id session-1
 
# OK: 34 chars
agentcore invoke "Hello" --session-id session-memory-test-001-first-conv

UUIDs (36 chars) always work. Watch the length when manually specifying session IDs.