Server generated an error 9002, Severity:17, State 6
The log file for database 'temdb' is full. Back up the transaction log for
the database to free up some log space.

tempdb.mdf file located at D:\Microsoft SQL Server\MSSQL\Data\ is with size
554,304KB. Harddisk still has plenty of space.

What is triggering the error. How to solve. Thank you