UCT8002 - Mapping rule for &1, row &2: Source field &3 does not exist

SAP Error Message - Details

• Message type: E = Error

• Message class: UCT8 - Message class for UCT8(mapping)

• Message number: 002

• Message text: Mapping rule for &1, row &2: Source field &3 does not exist

What causes this issue?

The mapping rule for target field &V1& uses the source field &V3& in row
&V2&. However, source field &V3& is <ZH>not </>in the list of source
fields. This error can have the following causes:
The data type originally defined in method Customizing was changed
afterwards (after mapping was defined). This made the source field
invalid.
The source data basis originally defined in method Customizing was
changed afterwards. The original source field exists, but <ZH>not </>in
the new source data basis.
The source data basis was changed afterwards - for example, it points to
a different InfoProvider or InfoObject catalog that does <ZH>not
</>contain the original source field.

System Response

The settings cannot be saved. The system issues an error message.

How to fix this error?

Do one of the following:
Choose an existing source field.
Check that the source data basis is defined correctly and (if
applicable) switch to another source data basis.

Procedure for System Administrators

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

Error message extract from SAP system. Copyright SAP SE.