System error on login attempt

[EnPa]

Our self-hosted Confluence 7.4.0 installation started suddenly to display a system error when a user tries to log in.

Wihtout logging in, everything works: I can see the pages, I cas use the search function, I can download attachments...

Buit when I try to login I get this message:

org.springframework.dao.InvalidDataAccessResourceUsageException: could not execute statement; SQL [n/a]; nested exception is org.hibernate.exception.SQLGrammarException: could not execute statement
    at org.springframework.orm.hibernate5.SessionFactoryUtils.convertHibernateAccessException(SessionFactoryUtils.java:230)

caused by: org.hibernate.exception.SQLGrammarException: could not execute statement
    at org.hibernate.exception.internal.SQLStateConversionDelegate.convert(SQLStateConversionDelegate.java:106)

caused by: com.microsoft.sqlserver.jdbc.SQLServerException: The transaction log for database 'confluence' is full due to 'LOG_BACKUP'.
    at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:262)

Users reported being able to log in yesterday without any issue. Today all users are affected.

No maintenance on the server has been carried out between yesterday and today.

Any idea what to look at?

Cheers, Enpa

[Nic Brough -Adaptavist-]

You've let the MS-SQL server run out of space.  See https://confluence.atlassian.com/jirakb/jira-server-fails-to-start-with-full-ms-sql-transaction-log-error-388399950.html and then, to fix it, https://docs.microsoft.com/en-us/sql/relational-databases/logs/troubleshoot-a-full-transaction-log-sql-server-error-9002?redirectedfrom=MSDN&view=sql-server-ver15

[EnPa]

Thank you for your very fast answer.

The IT departement cleaned the log and the issue is now gone :-)