Error 500 on /crashmanager/signatures/watch

⚠️ This seems to only affect instances using the Mysql database

I currently get a 500 on https://fuzzmanager.teklia.com/crashmanager/signatures/watch/ with the following log:

Traceback (most recent call last):
  File "/usr/local/lib/python3.8/site-packages/django/core/handlers/base.py", line 113, in _get_response
    response = wrapped_callback(request, *callback_args, **callback_kwargs)
  File "/src/server/crashmanager/views.py", line 172, in watchedSignatures
    newBuckets = list(buckets)
  File "/usr/local/lib/python3.8/site-packages/django/db/models/query.py", line 258, in __len__
    self._fetch_all()
  File "/usr/local/lib/python3.8/site-packages/django/db/models/query.py", line 1261, in _fetch_all
    self._result_cache = list(self._iterable_class(self))
  File "/usr/local/lib/python3.8/site-packages/django/db/models/query.py", line 57, in __iter__
    results = compiler.execute_sql(chunked_fetch=self.chunked_fetch, chunk_size=self.chunk_size)
  File "/usr/local/lib/python3.8/site-packages/django/db/models/sql/compiler.py", line 1154, in execute_sql
    cursor.execute(sql, params)
  File "/usr/local/lib/python3.8/site-packages/django/db/backends/utils.py", line 68, in execute
    return self._execute_with_wrappers(sql, params, many=False, executor=self._execute)
  File "/usr/local/lib/python3.8/site-packages/django/db/backends/utils.py", line 77, in _execute_with_wrappers
    return executor(sql, params, many, context)
  File "/usr/local/lib/python3.8/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/usr/local/lib/python3.8/site-packages/django/db/utils.py", line 90, in __exit__
    raise dj_exc_value.with_traceback(traceback) from exc_value
  File "/usr/local/lib/python3.8/site-packages/django/db/backends/utils.py", line 86, in _execute
    return self.cursor.execute(sql, params)
  File "/usr/local/lib/python3.8/site-packages/django/db/backends/mysql/base.py", line 74, in execute
    return self.cursor.execute(query, args)
  File "/usr/local/lib/python3.8/site-packages/MySQLdb/cursors.py", line 206, in execute
    res = self._query(query)
  File "/usr/local/lib/python3.8/site-packages/MySQLdb/cursors.py", line 319, in _query
    db.query(q)
  File "/usr/local/lib/python3.8/site-packages/MySQLdb/connections.py", line 259, in query
    _mysql.connection.query(self, query)
django.db.utils.OperationalError: (1055, "Expression #1 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'fuzzmanager.crashmanager_bucketwatch.lastCrash' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by")

This is not reproducible using sqlite on dev setups and could be tied to Mysql + djasngo.

I'm not sure it's worth spending time on that if you did not experience it on your own instances

Start in crashmanager/views.py at watchedSignatures, especially the queryset materialized at line 172. Reproduce the /crashmanager/signatures/watch endpoint against MySQL with only_full_group_by enabled and inspect the generated query. Done means the endpoint no longer returns a 500 on MySQL while preserving its existing behavior.