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<@ULVA73B9P> could suggest how handle these errors...
# marvin-ai
d
@Marvin could suggest how handle these errors on server:
m
✅ thought for 298.6 seconds
d
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File "/usr/local/lib/python3.12/site-packages/asyncpg/prepared_stmt.py", line 256, in __do_execute
    return await executor(protocol)
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "asyncpg/protocol/protocol.pyx", line 206, in bind_execute
TimeoutError
09:23:58.077 | ERROR   | prefect.server - Error running before-transition hook in rule <class 'prefect.server.orchestration.core_policy.SecureFlowConcurrencySlots'>: !TimeoutError()
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/prefect/server/orchestration/rules.py", line 651, in __aenter__
    await self.before_transition(*entry_context)
  File "/usr/local/lib/python3.12/site-packages/prefect/server/orchestration/core_policy.py", line 427, in before_transition
    acquired = await concurrency_limits_v2.bulk_increment_active_slots(
               ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/prefect/server/models/concurrency_limits_v2.py", line 208, in bulk_increment_active_slots
    result = await session.execute(query)
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/ext/asyncio/session.py", line 463, in execute
    result = await greenlet_spawn(
             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 203, in greenlet_spawn
    result = context.switch(value)
             ^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/orm/session.py", line 2365, in execute
    return self._execute_internal(
           ^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/orm/session.py", line 2251, in _execute_internal
    result: Result[Any] = compile_state_cls.orm_execute_statement(
                          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/orm/bulk_persistence.py", line 1660, in orm_execute_statement
    return super().orm_execute_statement(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/orm/context.py", line 306, in orm_execute_statement
    result = conn.execute(
             ^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1419, in execute
    return meth(
           ^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/sql/elements.py", line 526, in _execute_on_connection
    return connection._execute_clauseelement(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1641, in _execute_clauseelement
    ret = self._execute_context(
          ^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1846, in _execute_context
    return self._exec_single_context(
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1986, in _exec_single_context
    self._handle_dbapi_exception(
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 2358, in _handle_dbapi_exception
    raise exc_info[1].with_traceback(exc_info[2])
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/engine/base.py", line 1967, in _exec_single_context
    self.dialect.do_execute(
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/engine/default.py", line 951, in do_execute
    cursor.execute(statement, parameters)
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 580, in execute
    self._adapt_connection.await_(
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 132, in await_only
    return current.parent.switch(awaitable)  # type: ignore[no-any-return,attr-defined] # noqa: E501
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/util/_concurrency_py3k.py", line 196, in greenlet_spawn
    value = await result
            ^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 558, in _prepare_and_execute
    self._handle_exception(error)
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 508, in _handle_exception
    self._adapt_connection._handle_exception(error)
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 794, in _handle_exception
    raise error
  File "/usr/local/lib/python3.12/site-packages/sqlalchemy/dialects/postgresql/asyncpg.py", line 545, in _prepare_and_execute
    self._rows = deque(await prepared_stmt.fetch(*parameters))
                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/asyncpg/prepared_stmt.py", line 176, in fetch
    data = await self.__bind_execute(args, 0, timeout)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/asyncpg/prepared_stmt.py", line 267, in __bind_execute
    data, status, _ = await self.__do_execute(
                      ^^^^^^^^^^^^^^^^^^^^^^^^
  File "/usr/local/lib/python3.12/site-packages/asyncpg/prepared_stmt.py", line 256, in __do_execute
    return await executor(protocol)
           ^^^^^^^^^^^^^^^^^^^^^^^^
  File "asyncpg/protocol/protocol.pyx", line 206, in bind_execute
TimeoutError
09:23:58.098 | ERROR   | prefect - Error releasing concurrency slots on cleanup: Can't reconnect until invalid transaction is rolled back.  Please rollback() fully before proceeding (Background on this error at: <https://sqlalche.me/e/20/8s2b>)
09:23:58.109 | ERROR   | prefect.server - Encountered exception in request:
Traceback (most recent call last):
  File "/usr/local/lib/python3.12/site-packages/starlette/middleware/errors.py", line 164, in __call__
    await <http://self.app|self.app>(scope, receive, _send)
m
Happy to help! Could you share the exact error messages/stack traces you’re seeing and how you’re starting the server (command, environment, DB backend)? While you gather that, here’s a concise checklist for troubleshooting Prefect Server in 3.x. Assumptions: You’re on Prefect 3.x. Quick diagnostics - Show version and settings
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prefect version
prefect config view
Please share the values for 
PREFECT_API_URL
and any 
PREFECT_SERVER_*
you’ve set. - Start the server with debug logs (and optionally without services/UI to isolate issues)
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prefect server start --log-level DEBUG
# Optional isolations:
# prefect server start --no-services
# prefect server start --no-ui
- Health checks - Connectivity: hit the hello endpoint (replace with your API URL)
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curl -sSf ${PREFECT_API_URL%/}/api/hello
- Readiness/health endpoints are documented here: Health-check endpoints Common issues and fixes 1) Database migrations or schema errors - Upgrade DB:
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prefect server database upgrade -y
- If you’re stuck in a bad migration and can afford to wipe local data (destructive):
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prefect server database reset -y
- If using Postgres, ensure 
PREFECT_SERVER_DATABASE_CONNECTION_URL
is set correctly (see settings ref below). 2) Port already in use / binding errors - Change the port or stop the conflicting process:
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prefect server start --port 4201
3) SQLite “database is locked” - Stop any other server instance or background process using the same DB. - Consider Postgres for concurrency and stability. 4) CORS/UI not loading or API blocked - If you see CORS errors in the browser, configure CORS-related server settings (e.g., allowed origins/headers) and ensure your reverse proxy forwards the right headers and websockets. - Double-check that the UI is pointing at the correct API (
PREFECT_API_URL
) and that it’s reachable from the browser. 5) Reverse proxy / SSL - Terminate TLS at your proxy and forward 
X-Forwarded-*
headers. - Ensure the external 
PREFECT_UI_URL
and 
PREFECT_API_URL
match what users/clients access. - Verify websockets pass through your proxy. 6) Services not running (scheduler, late-run handling) - List and start services if you disabled `--no-services`:
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prefect server services ls
prefect server services start
Useful docs - Prefect Server overview - Settings reference (PREFECT_* env vars) - Health-check endpoints If you paste: - The exact error text - How you start the server (command + flags) - Your DB (SQLite or Postgres) and any relevant `PREFECT_SERVER_*`/`PREFECT_API_*` settings - Whether you’re behind a reverse proxy …I can pinpoint the fix quickly.
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