• Back up your data

  Before messing further, ensure all your ProSeries data, configurations, and any local files are backed up (databases, settings, etc.). You don’t want to lose work in the process.

• Run system integrity checks

  Use built-in Windows tools to check for corruption:

• Open Command Prompt as Administrator, run:

sfc /scannow

• Then:

DISM /Online /Cleanup-Image /RestoreHealth

• If errors are detected and fixed, reboot and test ProSeries again.

• Turn .NET Framework features off and back on

  • Go to Control Panel → Programs and Features → “Turn Windows features on or off.”

  • In there, uncheck the .NET Framework versions (e.g. 3.5, 4.x) to uninstall/disarm them.

  • Reboot.

  • Go back and re-check (turn back on) the required .NET versions.

  • Reboot again.

  This forces Windows to reinstall core .NET bits. (This is part of what standard guidance suggests for repairing .NET.)
  Run Microsoft’s .NET Framework Repair / Troubleshooter

  • Use Microsoft’s official troubleshooter for .NET Framework repair.

  • If there is a repair mode, let it attempt fixes.

  • Reboot, test ProSeries again.

• Remove recent updates (rollback)

  If you can identify which specific Windows update (or .NET cumulative update) coincided with the failure:

  • Go to Settings → Update & Security → Windows Update → View update history → Uninstall updates.

  • Uninstall the update(s) that hit around “2025-09” (or the suspect .NET/Windows patches).

  • Reboot and test ProSeries.

  Sometimes the offending update is what broke .NET.

• Clean reinstallation of ProSeries + .NET

  • Uninstall ProSeries entirely (via Control Panel → Uninstall a Program).

  • Uninstall or disable the .NET bits (via Windows Features as above).

  • Reboot.

  • Reinstall .NET first (using offline installer if possible).

  • Then install ProSeries (fresh), using the latest available installer from Intuit.

  • Reactivate / license it.

  Intuit’s support page has instructions for offline installers / updates.

• If all else fails: repair (in-place upgrade) Windows

  • Download the Windows 10 ISO (matching the same version/edition you currently have).

  • Mount or run setup from within Windows and choose “keep my files and apps” (repair upgrade).

  • This will reload core system components (including .NET) without wiping your apps or data.

  • After repair, test ProSeries.

  Many users have resorted to this when .NET is irreparably broken. Install updates after repair, carefully