PMS GSTR1 FAIL-SAFE CUSTOMER TEST BUILD
Build date: 01-Sep-2026

PURPOSE
This build keeps the existing Excel automation as the first option.
If Excel COM/open/repair/protected-view attempts all fail, it automatically
generates the GSTR1 XLSX without Excel and opens it through the Windows default app.

IMPORTANT SAFETY
1. Close PMS and all Excel/LibreOffice/OpenOffice windows before copying files.
2. Take a backup of the customer's current pmsGSTNet4.exe.
3. Do not replace or delete pms1.accdb, config files, customer data, or existing DLLs.

INSTALL ON CUSTOMER PC
1. Extract this ZIP into a temporary folder.
2. Copy pmsGSTNet4.exe into the customer's PMS application folder.
3. Copy both XLSX files from this package's OPERATION folder into the customer's
   PMS\OPERATION folder. Keep the same filenames.
4. Start PMS normally.

TEST
1. Generate GSTR1 with template V2.1 and confirm XLSX data and JSON generation.
2. Generate GSTR1 with template V2.2 and confirm XLSX data and JSON generation.
3. Test once with Excel available normally.
4. To confirm the independent fallback, test on the affected PC where the
   TYPE_E_LIBNOTREGISTERED Excel error was occurring.
5. Confirm the generated workbook exists under OPERATION\GSTUPDATE.

EXPECTED FAIL-SAFE ORDER
1. Normal Excel open.
2. Excel repair open.
3. Excel protected-view open.
4. Independent XLSX generation without Excel COM.

ROLLBACK
Close PMS and restore the backed-up pmsGSTNet4.exe. No database rollback is needed
because this package does not contain or replace the customer database.

DEPENDENCIES
No new third-party DLL is required. The fallback uses .NET Framework 4.7.2 libraries.
The existing Microsoft ACE provider is still used only when JSON is generated.

