After upgrade from JIRA 4.4.3 to 5.1.2 Issue creation is broken

[Jason King]

Last night we upgraded from 4.4.3 to the latest stable 5.1.2 We can no longer create issues, which is obviously a big deal for us ;) The upgrade went pretty smoothly and everything seems to work except this.. We really need some help. Thanks.

[Dave C]

This was caused by a known bug with the JIRA Toolkit Plugin, as described in JRA-19556.

[Norman Abramovitz]

What errors shows in your logs?

Chances are it is being caused by one or more plugins or your own customizations.

I would try disabling your existing plugins and see if create issues starts working, If it does, then enable your plugins one by one until the error returns.

Did you read all the upgrade release notes to see if they contain some special instructions?