Could you please confirm the exact version of Acrobat you are working on?
Check if there is any update available to the existing version. Launch Acrobat>Help>Check for update
If that doesn't work, then run a repair of the installation as suggested in help document. Launch Acrobat>Help>"Repair Installation"
Let us know if this doesn't work.
I am having the same problem. I am on version 17.009.20058 and on Windows 10. Yesterday all was working fine. Today no PDF document wants to open and on my emails the preview also does not work gives the message 'PDF Preview Handler'is not working.
Let me tell you what I have tried to date.
1. I have done a repair - made no difference. I am evidently on the latest update.
2. I have tried to uninstall but cannot do that as I get a message that there are programs using Adobe and I need to close them first. All programs are closed but I still get that same message.
3. Done the bit on task manager and there are no open programs - still get the same message that will not allow me to uninstall Adobe.
4. Have tried 'open with' also doesn't help.
5. I have checked the associate file protocol and that is correctly set as 'Adobe Acrobat Reader'.
6. Yesterday I was having problems that all my files were being saved as 'read only'. This I solved with running Adobe as Administrator but since then this other DDE server error comes up. I don't know if the two are related in any way.
Please help - I am desperate.