& open change pointers found for monitor object; threshold value is &

What causes this issue?

Performance attribute for the number of open change pointers in the
individual status groups.

How to fix this error?

If this threshold has been exceeded, you should use transaction BD21 to
process the open change pointers.

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

Error message extract from SAP system. Copyright SAP SE.