Ticket Number Format migration

Infos:

  • Used Zammad version: 3.2
  • Used Zammad installation source: repository RPM
  • Operating system: CentOS 7
  • Browser + version: Firefox 70

About the Ticket Number Format, we started with “Increment” and now we would like to move to “Date”.
The problem? The already existing, open tickets: if I change the ticket number format and after I reply to an email, a new ticket will be created instead of updating the old one.
Is there’s any way (even a manual, ticket by ticket one in the DB) to perform such a change?

Expected behavior:

Zammad does not create new tickets when receiving replies to existing ones.

Actual behavior:

Zammad creates new tickets when receiving replies to existing ones.

Steps to reproduce the behavior:

  1. Set the ticket number format to “Increment”
  2. Have a user send an email to automatically create the ticket
  3. Reply to the user
  4. Set the ticket number format to “Date”
  5. Have the user reply

A new ticket will be created and the old one won’t be updated.