Acrobat 2020 Sign-in Loop

Here’s a clean, natural-sounding English forum post you can use:

Hello everyone,

we are running into an issue with Acrobat Pro 2020 on a new device.
We own serial-number licenses, so normally on first launch we get prompted to sign in with any Adobe ID before we can enter the actual serial number. In the past, this first sign-in always worked (usually we just used the employee’s email/account).

However, on this new machine the initial login no longer works at all. After completing the sign-in process in Firefox, Acrobat simply jumps back to the previous “Sign-in required” window. This loops endlessly, no matter how many times we try.

In Chrome and Edge, the login doesn’t even complete, it just fails outright.

I’m aware that there are other posts about similar issues on the Forum, but unfortunately none of the suggested solutions have helped so far.

What I have tried already:

• Deleted all Adobe-related registry entries

• Removed all Adobe program folders and AppData folders

• Reinstalled Acrobat Pro 2020

• Tried different browsers (Chrome, Edge, Firefox)

• Tried multiple Adobe accounts

Has anyone experienced this issue recently or found a workaround?
Any help would be appreciated.

Program Version: 20.005.30680
Our installer is a bit old, so if there is a newer verison let me know 🙂

Thanks in advance!