Hope you are doing well and sorry for the trouble. As described the application is crashing on opening the second file.
Would you mind sharing the version of the Adobe Acrobat DC you are using? To check the version go to Help > About Acrobat and make sure you have the latest version 21.05.20058 installed. Go to Help > Check for updates and reboot the computer.
- Are you on MAc or Widows OS and what is its version. Please try to repair the installation (Win Only) from help menu > Repair Installation.
- If the file is located on a shared network/drive, please download it to your computer first and then try to open it and check.
- You may also try to turn off the protected mode for testing (Win Only) Go to Edit > Preferences > Enhanced Security > Uncheck 'Enable protected mode at startup' Turn off the protected mode and Uncheck 'Enhanced Security' > Click OK and reboot the computer. Note: Please turn on the security after testing to avoid any security risk.
You may also checkout the help pages listed below: