Oh frustrating one , but it usually stems from either resource constraints or issues like session termination or corruption. As @Anduin Xue mentioned, common causes include disk space problems, tempdb contention, or corrupted indexes.

To fix it, start with DBCC CHECKDB to confirm there’s no corruption. If no issues are found, check the tempdb configuration—it might need more space or additional files for better performance. Also, try running the index creation in single-user mode to avoid potential locking issues.

For a full troubleshooting guide, check this https://learn.microsoft.com/en-us/troubleshoot/sql/database-engine/database-file-operations/troubleshoot-dbcc-checkdb-errors. Let me know if it all works .