Opening new file closes existing file

Hi there

Hope you are doing well and sorry for the trouble. As described, opening new file closes the existing file.

Would you mind sharing the version of the Adobe Acrobat Reader DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest  version installed. Go to Help > Check for Updates and reboot the computer once and see if that helps.

Are you on Mac or Windows machine and what is the version of the OS? Please check for any missing/pending update for OS and try updating it and check

Please try to repair the installation (Win Only) and reboot the computer. Go to Help > Repair Installation.

If it still doesn't work please try to reset the Acrobat Preferences to default as described in the help page https://community.adobe.com/t5/acrobat/how-to-reset-acrobat-preference-settings-to-default/td-p/4792082 and check if that works

You may also try to create a new test user profile with full admin rights or enable the root account in Mac and try using the application there and check.

Regards

Amal