Migrating an instance can result in indexing being disabled

Summary

If an instance has an indexing directory that is not the default, it's possible to prevent indexing from occurring.

Steps to Reproduce

1. Restore an instance from a previous version of JIRA that had a customised index directory.
2. Go to the indexing page and attempt to index it.

Expected Results

The instance can be reindexed successfully.

Actual Results

Indexing is disabled and the instance cannot be reindexed through the browser.

The following appears in the logs:

2014-06-20 11:37:19,266 http-bio-8080-exec-23 WARN localadmin 697x62x1 16hinsb 127.0.0.1 /secure/admin/IndexAdmin.jspa [jira.issue.index.IndexConsistencyUtils] Index consistency check failed for index 'Issue': com.atlassian.jira.issue.index.SearchUnavailableException: java.lang.IllegalStateException: Indexing is disabled.

An error in the screenshot appears to the user also.

Workaround

This can be worked around as per After upgrading JIRA indexing is disabled.

Notes

This can also be disabled if the indexing directory is invalid:

2014-06-20 10:39:23,781 localhost-startStop-1 ERROR      [atlassian.jira.upgrade.ConsistencyCheckImpl] Indexing is turned on, but index path [/localdisk/var/jira/jira-index] invalid - disabling indexing