Acrobat Reader is unable to correctly interpret some mountpoint reparse points (junctions). In practical terms: Acrobat Reader is unable to access PDF files from file systems mounted as directories and this is the root cause of the problem.

Junctions are special symbolic links that are used in many scenarios; an important one is when a file system is mounted as a directory rather than a regular drive. Junctions contain 2 paths: a “substitute” path which must be a path in the NTOS namespace (not a Win32 path) and a “print” path, which is to be used for display to the user.

A junction that is used to mount a file system on a directory might have a target like \Device\Volume{GUID}, which might be a file system device. Unfortunately targets such as \Device\Volume{GUID} appear to create problems for Acrobat Reader because it interprets them as the Win32 path C:\Device\Volume{GUID}, which is incorrect.

For more information on this problem please see this GitHub issue:
https://github.com/billziss-gh/winfsp/issues/274

I am the author of the WinFsp software, which can be used to create file systems and I am happy to answer any questions you may have about this problem.

After opening Acrobat Reader DC (in a windowed mode, not in tabbed), it, for some mysterious reason, switches off the Windows 10 Explorer setting for windows to cast shadows. It results in focused folder windows becoming visually borderless, making it very difficult to work with them.
The problem was described here for Acrobat DC:
https://acrobat.uservoice.com/forums/590923-acrobat-for-windows-and-mac/suggestions/38822896-bug-shadows-disappear-on-windows-10-explorer-wind
but it fully (and even more irritably) applies to Acrobat Reader DC, too.

It seems that for some reason, Acrobat Reader changes (switches off) each time the inherent Windows setting which can be found in System > Visual Effects tab > Show shadows under windows checkbox.

The problem persist already for a long time, please fix it!

Since using Adobe Reader DC for PC, the last few updates have only increased the number of clicks required to do basic tasks. When saving a document, with either the CTRL + S key press or selecting Save from the file tree, there doesn't seem to be any necessity to have the window attached pop up. It's a similar feature to Office programs now, and really only makes the process take longer. Clicking on Choose a Different Folder just brings up the same save options we had in the past. This just creates more steps and wastes time.

To be clear, this dialogue appears when I press SAVE or CTRL S, not when I click on Save As.

I would like to turn a certain PDF into a .jpg and I do not anticipate a need to do this again in the near future. Seems a little out of touch to expect anyone to pay $15.00 for a month and “potentially” hundreds of dollars to use a service only once or twice in a year.
On your most economical plan, Adobe receives about half of a dollar per day and allows an unlimited number of document conversions , as well as other services.

Adobe should offer an alternative payment schedule of $1.00 per document,
up to, $3.00 for a 24 hour day of unlimited use.

This would be much more inviting to the casual customer and there is a high likelihood of more than 1,000 people per day wanting to use a pay-per-use service rather than long term commitments.

I have a legal copy of Acrobat Pro X (Creative Suite) that I love (I use it over Creative Cloud supplied by my employer). PROBLEM: I cannot have Reader DC (needed for shared forms sent to me occasionally) installed at the same time as it always acts as default app even though the Windows 10 default app still lists Acrobat Pro. This is as infuriating as when Edge automatically changes this every time there is a Windows update. I already own Finereader 15 that does everything Acrobat does and more and does not require a monthly subscription. You lost a customer when you made your business model change, but stop trying to control my computer.

For all of the machines in my Win 10 2004 test group, the Reader plugin for IE (AcroPDF64.dll) has lost the ability to start the print dialog, either from the handy button in the border UI, the drop down menu, or Ctrl+P. In all cases nothing happens. There are a variety of versions on the affected machines but most of them are quite current (20.9.20063 and ...65). The problem is restricted to IE (11 I have no other versions to check) and the new windows 10 2004 feature build.
If you're interested in any other data I can provide on the issue feel free to let me know.