Enter a valid posting date

What causes this issue?

You have assigned a posting variant to the current time base variant.
However, the date in the current line is not specified as a possible
posting date in the assigned posting variant.

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?

You can only specify dates as posting dates, if they are specified as
possible posting dates in the assigned posting variant.
Please do not mark the date of this line as a posting date. If you need
this date as a posting date, please assign another posting variant to
the time base variant.

Error message extract from SAP system. Copyright SAP SE.