sqlalchemy.exc.TimeoutError: QueuePool limit of size 5 overflow 10 reached, connection timed out

[taygun08]

ERROR

`2025-09-04 12:57:29 ERROR uvicorn.error - Exception in ASGI application

Traceback (most recent call last):
File "/home/ftuser/.local/lib/python3.13/site-packages/uvicorn/protocols/http/h11_impl.py", line 403, in run_asgi
result = await app( # type: ignore[func-returns-value]
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
self.scope, self.receive, self.send
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/home/ftuser/.local/lib/python3.13/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in call
return await self.app(scope, receive, send)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/fastapi/applications.py", line 1054, in call
await super().call(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/applications.py", line 113, in call
await self.middleware_stack(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/errors.py", line 186, in call
raise exc
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/errors.py", line 164, in call
await self.app(scope, receive, _send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/cors.py", line 85, in call
await self.app(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/exceptions.py", line 63, in call
await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
raise exc
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
await app(scope, receive, sender)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 716, in call
await self.middleware_stack(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 736, in app
await route.handle(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 290, in handle
await self.app(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 78, in app
await wrap_app_handling_exceptions(app, request)(scope, receive, send)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app
raise exc
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app
await app(scope, receive, sender)
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 75, in app
response = await f(request)
^^^^^^^^^^^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/fastapi/routing.py", line 302, in app
raw_response = await run_endpoint_function(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
...<3 lines>...
)
^
File "/home/ftuser/.local/lib/python3.13/site-packages/fastapi/routing.py", line 215, in run_endpoint_function
return await run_in_threadpool(dependant.call, **values)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/concurrency.py", line 38, in run_in_threadpool
return await anyio.to_thread.run_sync(func)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/anyio/to_thread.py", line 56, in run_sync
return await get_async_backend().run_sync_in_worker_thread(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
func, args, abandon_on_cancel=abandon_on_cancel, limiter=limiter
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/home/ftuser/.local/lib/python3.13/site-packages/anyio/_backends/_asyncio.py", line 2476, in run_sync_in_worker_thread
return await future
^^^^^^^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/anyio/_backends/_asyncio.py", line 967, in run
result = context.run(func, *args)
File "/freqtrade/freqtrade/rpc/api_server/api_v1.py", line 117, in balance
return rpc._rpc_balance(
~~~~~~~~~~~~~~~~^
config["stake_currency"],
^^^^^^^^^^^^^^^^^^^^^^^^^
config.get("fiat_display_currency", ""),
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
)
^
File "/freqtrade/freqtrade/rpc/rpc.py", line 777, in _rpc_balance
open_trades: list[Trade] = Trade.get_open_trades()
~~~~~~~~~~~~~~~~~~~~~^^
File "/freqtrade/freqtrade/persistence/trade_model.py", line 1504, in get_open_trades
return Trade.get_trades_proxy(is_open=True)
~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
File "/freqtrade/freqtrade/persistence/trade_model.py", line 1797, in get_trades_proxy
return cast(list[LocalTrade], Trade.get_trades(trade_filter).all())
~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^
File "/freqtrade/freqtrade/persistence/trade_model.py", line 1842, in get_trades
return Trade.session.scalars(query)
~~~~~~~~~~~~~~~~~~~~~^^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/scoping.py", line 1905, in scalars
return self._proxied.scalars(
~~~~~~~~~~~~~~~~~~~~~^
statement,
^^^^^^^^^^
...<3 lines>...
**kw,
^^^^^
)
^
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 2473, in scalars
return self._execute_internal(
~~~~~~~~~~~~~~~~~~~~~~^
statement,
^^^^^^^^^^
...<4 lines>...
**kw,
^^^^^
).scalars()
^
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 2241, in _execute_internal
conn = self._connection_for_bind(bind)
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 2110, in _connection_for_bind
return trans._connection_for_bind(engine, execution_options)
~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "", line 2, in _connection_for_bind
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/state_changes.py", line 139, in _go
ret_value = fn(self, *arg, **kw)
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 1189, in _connection_for_bind
conn = bind.connect()
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 3273, in connect
return self._connection_cls(self)
~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 145, in init
self._dbapi_connection = engine.raw_connection()
~~~~~~~~~~~~~~~~~~~~~^^
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 3297, in raw_connection
return self.pool.connect()
~~~~~~~~~~~~~~~~~^^
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/base.py", line 449, in connect
return _ConnectionFairy._checkout(self)
~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/base.py", line 1264, in _checkout
fairy = _ConnectionRecord.checkout(pool)
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/base.py", line 713, in checkout
rec = pool._do_get()
File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/impl.py", line 168, in _do_get
raise exc.TimeoutError(
...<4 lines>...
)
sqlalchemy.exc.TimeoutError: QueuePool limit of size 5 overflow 10 reached, connection timed out, timeout 30.00 (Background on this error at: https://sqlalche.me/e/20/3o7r)`

[iterativv]

Never encountered this. It was temporary issue and now is working well or still the same issue persists ?

[willvin313]

ERROR

`2025-09-04 12:57:29 ERROR uvicorn.error - Exception in ASGI application

Traceback (most recent call last): File "/home/ftuser/.local/lib/python3.13/site-packages/uvicorn/protocols/http/h11_impl.py", line 403, in run_asgi result = await app( # type: ignore[func-returns-value] ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ self.scope, self.receive, self.send ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ) ^ File "/home/ftuser/.local/lib/python3.13/site-packages/uvicorn/middleware/proxy_headers.py", line 60, in call return await self.app(scope, receive, send) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/fastapi/applications.py", line 1054, in call await super().call(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/applications.py", line 113, in call await self.middleware_stack(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/errors.py", line 186, in call raise exc File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/errors.py", line 164, in call await self.app(scope, receive, _send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/cors.py", line 85, in call await self.app(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/middleware/exceptions.py", line 63, in call await wrap_app_handling_exceptions(self.app, conn)(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app raise exc File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app await app(scope, receive, sender) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 716, in call await self.middleware_stack(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 736, in app await route.handle(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 290, in handle await self.app(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 78, in app await wrap_app_handling_exceptions(app, request)(scope, receive, send) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 53, in wrapped_app raise exc File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/_exception_handler.py", line 42, in wrapped_app await app(scope, receive, sender) File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/routing.py", line 75, in app response = await f(request) ^^^^^^^^^^^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/fastapi/routing.py", line 302, in app raw_response = await run_endpoint_function( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ...<3 lines>... ) ^ File "/home/ftuser/.local/lib/python3.13/site-packages/fastapi/routing.py", line 215, in run_endpoint_function return await run_in_threadpool(dependant.call, **values) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/starlette/concurrency.py", line 38, in run_in_threadpool return await anyio.to_thread.run_sync(func) ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/anyio/to_thread.py", line 56, in run_sync return await get_async_backend().run_sync_in_worker_thread( ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ func, args, abandon_on_cancel=abandon_on_cancel, limiter=limiter ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ) ^ File "/home/ftuser/.local/lib/python3.13/site-packages/anyio/_backends/_asyncio.py", line 2476, in run_sync_in_worker_thread return await future ^^^^^^^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/anyio/_backends/_asyncio.py", line 967, in run result = context.run(func, *args) File "/freqtrade/freqtrade/rpc/api_server/api_v1.py", line 117, in balance return rpc._rpc_balance( ~~~~~~~~~~~~~~~~^ config["stake_currency"], ^^^^^^^^^^^^^^^^^^^^^^^^^ config.get("fiat_display_currency", ""), ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ ) ^ File "/freqtrade/freqtrade/rpc/rpc.py", line 777, in _rpc_balance open_trades: list[Trade] = Trade.get_open_trades() ~~~~~~~~~~~~~~~~~~~~~^^ File "/freqtrade/freqtrade/persistence/trade_model.py", line 1504, in get_open_trades return Trade.get_trades_proxy(is_open=True) ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^ File "/freqtrade/freqtrade/persistence/trade_model.py", line 1797, in get_trades_proxy return cast(list[LocalTrade], Trade.get_trades(trade_filter).all()) ~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^ File "/freqtrade/freqtrade/persistence/trade_model.py", line 1842, in get_trades return Trade.session.scalars(query) ~~~~~~~~~~~~~~~~~~~~~^^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/scoping.py", line 1905, in scalars return self._proxied.scalars( ~~~~~~~~~~~~~~~~~~~~~^ statement, ^^^^^^^^^^ ...<3 lines>... **kw, ^^^^^ ) ^ File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 2473, in scalars return self._execute_internal( ~~~~~~~~~~~~~~~~~~~~~~^ statement, ^^^^^^^^^^ ...<4 lines>... **kw, ^^^^^ ).scalars() ^ File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 2241, in _execute_internal conn = self._connection_for_bind(bind) File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 2110, in _connection_for_bind return trans._connection_for_bind(engine, execution_options) ~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^^^^^^^^^^^^^ File "", line 2, in _connection_for_bind File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/state_changes.py", line 139, in _go ret_value = fn(self, *arg, **kw) File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/orm/session.py", line 1189, in _connection_for_bind conn = bind.connect() File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 3273, in connect return self._connection_cls(self) ~~~~~~~~~~~~~~~~~~~~^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 145, in init self._dbapi_connection = engine.raw_connection() ~~~~~~~~~~~~~~~~~~~~~^^ File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/engine/base.py", line 3297, in raw_connection return self.pool.connect() ~~~~~~~~~~~~~~~~~^^ File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/base.py", line 449, in connect return _ConnectionFairy._checkout(self) ~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^ File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/base.py", line 1264, in _checkout fairy = _ConnectionRecord.checkout(pool) File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/base.py", line 713, in checkout rec = pool._do_get() File "/home/ftuser/.local/lib/python3.13/site-packages/sqlalchemy/pool/impl.py", line 168, in _do_get raise exc.TimeoutError( ...<4 lines>... ) sqlalchemy.exc.TimeoutError: QueuePool limit of size 5 overflow 10 reached, connection timed out, timeout 30.00 (Background on this error at: https://sqlalche.me/e/20/3o7r)`%60)

Root Cause
The error occurs at the SQLAlchemy level with this key message:
sqlalchemy.exc.TimeoutError: QueuePool limit of size 5 overflow 10 reached, connection timed out, timeout 30.00

This means:
SQLAlchemy's connection pool is configured with 5 connections + 10 overflow connections (15 total)
All 15 connections are currently in use or stuck
When FreqTrade tries to query open trades for the balance endpoint, it can't get a database connection within the 30-second timeout

What Triggered It
The error was triggered when the API server tried to fetch the account balance (/balance endpoint), which requires querying open trades from the database.

Likely Causes
Database Connection Leaks: Previous database operations didn't properly close connections, leaving them hanging
Long-Running Queries: Some database queries are taking too long, blocking the connection pool
High Concurrent Load: Too many simultaneous API requests or bot operations
Database Lock/Deadlock: The database itself might be experiencing issues
Network Issues: Slow network between FreqTrade and the database

Solutions
Restart FreqTrade: This will reset the connection pool and clear any stuck connections
Check Database Performance: Look for slow queries or locks in your database
Increase Connection Pool Size: Modify your FreqTrade config to allow more database connections
Review Recent Changes: Any recent config changes or high trading activity that might have triggered this
Monitor Resource Usage: Check if your system is running low on memory or CPU

The immediate fix is usually to restart FreqTrade, but you should also investigate what caused the connection pool to become exhausted to prevent it from happening again.