Resource &1 is missing in planning version &2 of model &3

What causes this issue?

The system has checked if resource &V1& exists in all planning versions
for the model and if it is model-independent. In doing this, the system
determined that resource &V1& is missing from planning version &V2& of
model &V3&.

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?

Delete the resource from model &V3& and then reassign it. By doing
this, the resource will be created again in all versions of the model,
including planning version &V2&.

Procedure for System Administrators

Error message extract from SAP system. Copyright SAP SE.