This error usually happens when another program, such as Adobe Reader or your default PDF viewer, is frozen or busy. Follow these solutions in order:
Close and reopen your PDF viewer
Press Ctrl + Shift + Esc to open Task Manager.
Under the Processes tab, look for Adobe Reader, Foxit, or any PDF-related app.
Right-click the app and select End Task.
Reopen your PDF and check if the issue is resolved.
Restart your computer
A simple restart can close any frozen programs and free up system resources.
Use a different PDF viewer
Try opening the PDF with Google Chrome, Microsoft Edge, or another PDF reader.
To do this:
Right-click the PDF file.
Select Open with and choose a different viewer.
Check for Windows updates
Software conflicts can sometimes be fixed by installing the latest updates.
Go to settings, update & security, Windows Update.
Click check for updates and install any available updates.
Repair or Reinstall Your PDF Reader
Open Adobe Reader
Go to help, repair the installation
Note: If none of the above solutions work, consider checking for system errors or using an alternative PDF viewer.