&4 &3 for logical system &2 blocked by user &1

What causes this issue?

&V4& &V3& for logical system &V2& in the Investment Management
summarization database is currently blocked by user &V1&.

System Response

Processing is terminated.

How to fix this error?

Try again when user &V1& has finished processing the data.

Error message extract from SAP system. Copyright SAP SE.