Try Microsoft Edge
A fast and secure browser that's designed for Windows 10
You cannot base a date calculation on an undefined date.
Date: 0DFormula: 1M.
While running the Debugger it flows in to GST Management Code Unit
IF PostingDate < CALCDATE('<1M>',LastClosedDate) THEN ERROR( STRSUBSTNO( PeriodClosedErr,CALCDATE('<-1D>',CALCDATE('<1M>',LastClosedDate)), CALCDATE('<1M>',LastClosedDate))); GSTAccountingPeriod.GET("Accounting Period Start Date"); END ELSE ERROR(AccountingPeriodErr,PostingDate); END;
Please check if the accounting period for the calculation date is closed?
judging by the error it looks like LastClosedDate is blank (0D) and NAV cannot add date formulas to blank dates. I would say it's the issue with the code, as system should check if the LastClsoedDate is not blank before trying to call CALCDATE with it. If that's a standard Codeunit with no mods, it's worth checking for cumulative updates with the fix.
You need to create GST accounting period for the previous month and close it.
This is because system is checking for if the gst settlement is posted for the previous month.