SAP Message VF206 - The last possible number is assigned in document number assignment

Diagnosis
Document number assignment for the number range object &V1& in thenumber range &V2& has assigned the last number. Further numberassignment would lead to a termination, if the number range definitionis not manually changed.

Procedure
You can either increase the upper limit of the number range interval orset the current status back. You should however make sure that a
number is not assigned more than once in the future.