No external key found for the PSP element & in field &

What causes this issue?

The internal database key for a PSP element has been transferred in
field &v2&. The internal key must be converted into the external name.
An external name could not be found for the value &v1&.

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?

Check the transferred value.
Does the PSP element exist in the system?
Has the internal database key been transferred correctly?

Error message extract from SAP system. Copyright SAP SE.