When you send a release to JIRA from Aha! a new Version is created in JIRA. This error indicates that the version in JIRA that was created by Aha! has been deleted in JIRA. This means that the link from the Aha! release to the JIRA version is now broken.
The solution is to break the link so that Aha! creates a new version in JIRA. In Aha! go to the Releases -> Details screen for the release that this error relates to. Click on the trash can icon next to the link to the JIRA version.
When you send the release (or features in the release) to JIRA again a new version will be created, or if an existing version with the same name already exists it will be linked, for this release in Aha!