Usually this exception is caused by an out of disk space error. See KB article What causes the Exception: Out of disk space?
The fix is to ensure that the QIE server has free disk space available.
Once the disk space has been resolved and QIE is back up and running if you experience any anomalies with QIE then it is possible that the database was corrupted when it encountered this error. If this is the case, then the H2 database would need to be re-created.
