Converting a Sub-task of a Next-gen project to issue results in error 500

Issue Summary

When converting a Sub-task to issue (from a Next-gen project), the process will result in an error 500 in the end.

Environment

Jira Cloud.

Steps to Reproduce

• Perform a search that will return Sub-tasks of a Next-gen project;
• Hover over the line where one of those Sub-tasks is:
  • Click on the ellipses button next to it -> Convert to Issue.

See the recording: Convert to issue.mp4

Expected Results

The conversion will occur normally.

Actual Results

The process ends in an error 500.

Notes

It seems like if you have the Story issue type added in the project, the process will still end in an error 500, but the conversion will occur.

That happened even after I've removed the Story issue type from the project.

Workaround

Adding the Story issue type to the project may force the conversion to occur despite the error 500.

You might need to convert the Sub-task to Story first, and then change the issue type as desired.