Getting the 'Invalid class string' error on VAT Forms or GSTRs?

How to solve 'Invalid class string' & other errors in generating VAT Forms or GSTR ?


Error: Cannot open table =0 OR Mishandled Exception
Solution: Please go to Utility Menu->User Defined Query
Delete all query rows (records) with type = "V"

Run System->GST Updates->Update GST Tax Master


Error: Qrydtl.ftp or any other error with file starting with Qry
Solution: Delete from data directory -> qry*.dbf and run the software again.

Run System->GST Updates->Update GST Tax Master



Error: Index and length must refer to a location within the string. Parameter name:length

Solution: Please Run System->Facilities->Product->Update Tax Code

Error: Invalid class string. Solution: Please follow the steps below

Please Register Vatforms.dll or Analysis.dll by following below step.


Open CMD promt run as Administrator and run following commands.

(Exe Path) is E:\us162 in following lines. It is to be changed with E:\CS162 or as required.

C:\Windows\Microsoft.net\Framework\v4.0.30319\regasm E:\us162\vatforms.dll /codebase

C:\Windows\Microsoft.net\Framework\v4.0.30319\regasm E:\us162\analysis.dll /codebase

If you are using windows earlier version, in some cases, your problem is not solved after trying above step. In such case please follow following step and after completion of this step run above step. In  this case you may need online support. 

Now please register DLL files as outlined at starting of this document.

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