I have been pulling my hair out on this issue for some time now. Here is the story. I have just recently upgraded some of my machines to Solidwors 2017 sp2. With that the engineers use Solidworks Explorer to access workgroup PDM. We installed Adobe Acrobat DC on their machines and as soon as that happened, they were no longer able to preview PDF's in Solidworks Explorer without it giving an adobe error. The error message mentions Adobe Reader/Acrobat failed and Adobe error 9:9. I can get the exact message later.
However, if install reader alongside Acrobat, while letting Acrobat retain all its program defaults, I can preview files no problem. It's only when Acrobat is the only pdf editor installed that it does not work.
This has happened on Win 10 machines, as well as a sandbox virtual Win 7 machine I spun up to test this issue with. The only thing i can think of is that when Reader is installed and Acrobat has all associated defaults there is 1 protocol associated with Reader. Picture attached for reference. When reader is uninstalled, that protocol is gone and acrobat can no longer preview files in Solidworks PDM.
This problem is only related to the PDM preview. In regular Solidworks explorer, you can preview PDF's without issue. I have tried to follow the advice given here
https://forum.solidworks.com/thread/98575 but i am not using enterprise pdm, and I cannot seem to find a related reg key. I have searched high and low. Any help would be appreciated!