Exclusive TSN not received because object &2 is locked by user &1

What causes this issue?

This application has requested an exclusive TSN (Transaction Sequence
Number) but the TSN has not been received. The system tried for &V4&
seconds to lock object &V2& exclusively. However, table &V3& was locked
by user &V1& in a different SAP transaction.

System Response

Once the maximum waiting time of &V4& seconds has expired, the system
will stop trying to lock object &V2& exclusively.

How to fix this error?

Procedure for System Administrators

In the lock table (Tools > Administration ==> Monitor -> Lock Entries or
Transaction SM12), check which work process has locked object &V2& and
how long the object has been locked. Check if the process that set the
lock is still active. For example, an application process that writes to
the delta queue might have set a read lock. Then the process terminates
with a core dump, without deleting the lock. In this case, you can
delete the lock entry from the lock table manually.

Error message extract from SAP system. Copyright SAP SE.