Version conflict: Incompatible version of collector and applications

What causes this issue?

The version of the collector is not compatible with the disp+work of
the application server.

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?

Start the correct collector. The old collector might still run after
release upgrade from 1.2A to 2.0A.

Error message extract from SAP system. Copyright SAP SE.