No totals for postable documents exist

What causes this issue?

The system could not determine any totals for physical inventory
documents with postable inventory differences.
Possible reasons for this are:
No documents with postable inventory differences exist.
No count has been entered yet for the open physical inventory documents.

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?

Error message extract from SAP system. Copyright SAP SE.