broken encoding

[MinkaKaraivanova]

MediaCMS running as dockered installation on an Ubuntu 22.04.5 LTS.

Mediacms was upgraded from 7.6.0 to 8.0.8 using

 docker pull mediacms/mediacms:full

Initial testing: after a video was uploaded, the Encoding to the
different Ecoding profiles does not start. In the Django interface,
the encodings are reported as Pending. In some cases, they are
reported as Failed.

All DB migrations during the upgrade are done successfully.

The hypothesis is that after the celery worker container starts it
initializes the django application; django loads installed apps and
among them lti. And when ensure_keys_exist() is run, it touches the
database (we see django warnings like: Accessing the database during app
initialization is discouraged). When celery forks the forks its worker
children, they inherit a bad/half-used database connection. From here
on any query a child performs would fail. Django raises errors like

the last operation didn't produce a result can't change 'autocommit' 
now: connection in transaction status INTRANS

lti (and apps.py) seems to be introduced in v7.7.0 on 11th of May 2026.

If lti/apps.py (in the celery_worker container) is changed to the following, encoding starts working
after restart of that container only and when new video is uploaded.

from django.apps import AppConfig

class LtiConfig(AppConfig):
    default_auto_field = 'django.db.models.BigAutoField'
    name = 'lti'
    verbose_name = 'LTI 1.3 Integration'
	    
    def ready(self):
       pass

Searching through the logs (celery_long.log), this is the first error seen in connection
to the encodings is shown at the end of the message.

[2026-05-16 20:38:58,737: ERROR/ForkPoolWorker-4] Task encode_media[eee3c319-aa1a-4ac5-849f-365e6f723f7f] raised unexpected: ProgrammingError("the last operation didn't produce a result")
Traceback (most recent call last):
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/utils.py", line 98, in inner
    return func(*args, **kwargs)
  File "/home/mediacms.io/lib/python3.13/site-packages/psycopg/cursor.py", line 190, in fetchone
    self._check_result_for_fetch()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/mediacms.io/lib/python3.13/site-packages/psycopg/_cursor_base.py", line 588, in _check_result_for_fetch
    raise e.ProgrammingError("the last operation didn't produce a result")
psycopg.ProgrammingError: the last operation didn't produce a result

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "/home/mediacms.io/lib/python3.13/site-packages/celery/app/trace.py", line 453, in trace_task
    R = retval = fun(*args, **kwargs)
                 ~~~^^^^^^^^^^^^^^^^^
  File "/home/mediacms.io/lib/python3.13/site-packages/celery/app/trace.py", line 736, in __protected_call__
    return self.run(*args, **kwargs)
           ~~~~~~~~^^^^^^^^^^^^^^^^^
  File "/home/mediacms.io/mediacms/files/tasks.py", line 257, in encode_media
    if not Encoding.objects.filter(id=encoding_id).exists():
           ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/models/query.py", line 1296, in exists
    return self.query.has_results(using=self.db)
           ~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^^^
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/models/sql/query.py", line 674, in has_results
    return compiler.has_results()
           ~~~~~~~~~~~~~~~~~~~~^^
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/models/sql/compiler.py", line 1591, in has_results
    return bool(self.execute_sql(SINGLE))
                ~~~~~~~~~~~~~~~~^^^^^^^^
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/models/sql/compiler.py", line 1639, in execute_sql
    val = cursor.fetchone()
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/utils.py", line 97, in inner
    with self:
         ^^^^
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/utils.py", line 91, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/home/mediacms.io/lib/python3.13/site-packages/django/db/utils.py", line 98, in inner
    return func(*args, **kwargs)
  File "/home/mediacms.io/lib/python3.13/site-packages/psycopg/cursor.py", line 190, in fetchone
    self._check_result_for_fetch()
    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^
  File "/home/mediacms.io/lib/python3.13/site-packages/psycopg/_cursor_base.py", line 588, in _check_result_for_fetch
    raise e.ProgrammingError("the last operation didn't produce a result")
django.db.utils.ProgrammingError: the last operation didn't produce a result
[2026-05-16 20:38:58,741: WARNING/ForkPoolWorker-4] rolling back returned connection: <psycopg.Connection [INTRANS] (host=db database=mediacms) at 0x7f17ed20d090>

[mgogoulos]

does the issue get resolved after a Docker compose restart web/celery_worker?

[mgogoulos]

I just pushed a new release, 8.1.2 which removes this check you mention above, since it's redundant anyways.

[mgogoulos]

thanks for reporting @MinkaKaraivanova