Processing terminated due to error. Alert level > 7

What causes this issue?

For exception reporting alerts were found with an alert level greater
than 7. During processing of reporting agent packets in a process chain
the status "terminated with error" was therefore reported back to the
process chain.
This occurs so you can react to alert levels greater than 7 in the
process chain.
Example: In the process chain data consistency is checked after data is
loaded using the process type agent exception reporting If data
inconsistencies are found in exception reporting (Alert level > 7)
processing in the process chain is canceled.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.