Issue Summary

Importing Jira Issues in Cloud using External System Import fails if the project has large number of existing issues.

Steps to Reproduce

1. Navigate to System Settings > External System Import
2. Use any csv with 5-10 rows on old Import Experience.
3. Select projet having large number of issues [more than 1 million]and click on next button to navigate to "map Project field" screen.
4. Map the fields .
5. Click "Begin Import".

Expected Results

• Import is successful.

Actual Results

• We get error - Unexpected failure occurred. Importer will stop immediately. Data may be in an unstable state
  In HAR logs, we see 404 error.

Workaround

• Please  split project issues into 2 or more projects or create a new project to import issues.