If the file is missing entirely, skip to Solution 5.

Use the Ctrl + F search function within Registry Editor to search for acrosup64.dll .

: Corrupted system files can trigger DLL errors. Run sfc /scannow in an Administrative Command Prompt to repair Windows system files.

This usually happens due to:

If the cleanup tool misses localized configurations, manual deletion forces Windows to recreate the installer tracking directory. Press Win + R , type %localappdata% , and press Enter.

Online installers download fragments of data dynamically. If a network packet drops, the installer payload can corrupt, triggering the "not marked for installation" error.

10. Manually edit Registry 11. Restore Windows to earlier point 12. Contact Adobe Support

Look for the or Standalone offline installer .

Download the official tool from the Adobe Reader and Acrobat Cleaner Tool .

Once you resolve "acrosup64.dll is not marked for installation," follow these best practices to avoid recurrence:

Open Run again, type %appdata% (which opens the Roaming folder), and delete the folder there as well.

If the above methods fail, use a specialized utility to clean the Windows Installer database.

Look for residual folders related to the specific version failing to install and delete them.