Zammad system not processing emails

Hello @MrGeneration

Thank’s for your reply.

You’re right i can see deadlocks timeout from the database logs:

Process 23239 waits for ShareLock on transaction 28677595; blocked by process 9304.
	Process 9304 waits for ShareLock on transaction 28677594; blocked by process 23239.
	Process 23239: SELECT  "taskbars".* FROM "taskbars" WHERE "taskbars"."id" = $1 LIMIT $2 FOR UPDATE
	Process 9304: SELECT  "taskbars".* FROM "taskbars" WHERE "taskbars"."id" = $1 LIMIT $2 FOR UPDATE

I think raising the deadlock timeout could fix it, otherwise an upgrade of the zammad version is required regarding this post: [solved] Failed to run scheduled job 'Generate user based stats.'. Cause: Failed to run Stats.generate after 10 tries #<RuntimeError: No settings with area 'Dashboard::Stats' defined>

Please what do you suggest?

To answer your questions:

• Is this a Zammad installation with any manual changes?
Yes, the change i did is i have increased the amount of the application server by executing
this command:
zammad config:set WEB_CONCURRENCY=2

• What was the last change before this issue arised?
The last change is that the database was upgraded to postgresql11-server-11.5.(Installed in a separate machine).

Please found out the output of the following commands (zammad run rails c):

Overview.count:
=> 19

User.count:
=> 5442

User.joins(roles: :permissions).where(roles: { active: true }, permissions: { name: 'ticket.agent', active: true }).where.not(id: 1).count:
=> 60

Ticket.count:
=> 33908

Organization.count:
=> 5

Extra:
Hardware information: 2x4 CPU Cores and 16GB RAM.

Thank’s for your support.