Posting key & does not permit specification of a special G/L indicator

What causes this issue?

Posting key '&v1&' and special G/L indicator '&v2&' were transferred.

System Response

Inconsistent data cannot be prcessed.

How to fix this error?

Remove the special G/L indicator online.
If the data comes from another application, the consistency of the data
there must be guaranteed.

Error message extract from SAP system. Copyright SAP SE.