Failed to schedule task

The traceback points to raise Exception("Failed to schedule task") in /ex_app/lib/nc_model.py at _schedule_task (line 210), reached from _astream (line 368) during the agent's call_model in lib/agent.py. Start by reading why _schedule_task returns no task, and check how the Nextcloud task-scheduling call behaves when it fails. Done means the root cause of the scheduling failure is identified and the error path is handled or explained. Reproducing it needs a running Nextcloud with the context_agent app, so ask the reporter for the steps first.

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Steps to reproduce

1. It gave this error, so I just turned it off, unregistered it, put it back on and it still came up.

Expected behaviour

Tell us what should happen

Actual behaviour

Tell us what happens instead, if possible also add a screenshot

I only just noticed this happening, so I don't know if it'll persist, but here's the logs.

2026-10-16 00:06:16,900 - context_agent - INFO - New Task incoming
2026-10-16 00:06:17,071 - context_agent - INFO - {'type': 'core:contextagent:multimodal-interaction', 'input': 'Can you see the last 10 emails that came from *****.', 'confirmation': 0, 'conversation_token': '', 'memories': [], 'input_attachments': []}
/ex_app/lib/all_tools/calendar.py:21: DeprecationWarning: Sync Nextcloud/NextcloudApp classes are deprecated and will be removed in v0.31.0. Migrate to AsyncNextcloud/AsyncNextcloudApp.
ncSync = NextcloudApp()
2026-10-16 00:06:42,571 - context_agent - ERROR - Error: Traceback (most recent call last):
File "/ex_app/lib/main.py", line 268, in handle_task
output = await react(task, nextcloud, stream_output=stream_output if stream_updates_enabled else None)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/ex_app/lib/agent.py", line 262, in react
async for event in graph.astream(new_input, thread, stream_mode=stream_mode):
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/pregel/main.py", line 3000, in astream
async for _ in runner.atick(
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/pregel/_runner.py", line 410, in atick
_panic_or_proceed(
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/pregel/_runner.py", line 520, in _panic_or_proceed
raise exc
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/pregel/_retry.py", line 137, in arun_with_retry
return await task.proc.ainvoke(task.input, config)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/_internal/_runnable.py", line 705, in ainvoke
input = await asyncio.create_task(
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langgraph/_internal/_runnable.py", line 473, in ainvoke
ret = await self.afunc(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/ex_app/lib/agent.py", line 195, in call_model
response = await bound_model.ainvoke([system_prompt] + state["messages"], config)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 417, in ainvoke
llm_result = await self.agenerate_prompt(
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 1036, in agenerate_prompt
return await self.agenerate(
^^^^^^^^^^^^^^^^^^^^^
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 994, in agenerate
raise exceptions[0]
File "/root/.cache/pypoetry/virtualenvs/context-agent-il7asoJj-py3.11/lib/python3.11/site-packages/langchain_core/language_models/chat_models.py", line 1153, in _agenerate_with_cache
async for chunk in self._astream(messages, stop=stop, **kwargs):
File "/ex_app/lib/nc_model.py", line 368, in _astream
task = await self._schedule_task(task_input, prefer_streaming=True)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/ex_app/lib/nc_model.py", line 210, in _schedule_task
raise Exception("Failed to schedule task")
Exception: Failed to schedule task
During task with name 'agent' and id 'b480648f-e5b8-7d04-cd7b-3e1d0d2d2b77'

Server configuration

Web server: Apache

Database: MariaDB

PHP version: 8.5

Nextcloud version: (see Nextcloud admin page)
35.0.2

If you have access to your command line run e.g.:
sudo -u www-data php occ app:list
from within your Nextcloud installation folder

If you have access to your command line run e.g.:
sudo -u www-data php occ config:list system
from within your Nextcloud installation folder

Browser

Browser name: Firefox/Chrome/Safari/…

Browser version: 124/125/…

Operating system: Windows/Ubuntu/Mac/…

Insert your browser log here, this could for example include:
a) The javascript console log
b) The network log
c) ...