Internal error: Table field for variable & cannot be determined

What causes this issue?

An error occurred when importing or generating a report. The report
uses an additional variable in a formula variable which belongs to a
field that does not match the formula result.
Additionally, the affected variable does not belong to the report
table.

System Response

The report cannot be imported.

How to fix this error?

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.