Digital Editions 4.5 won't open

This fix actually works:

You must delete the Adobe ADE file contained in C:\Users\User\AppData\Local.

Delete the ADE folder here (NOT Adobe Acrobat).

Then relaunch ADE and the EXE file will load ADE properly.

I received the following solution from Kobo Customer Support: Irais E. Thank you Irais! THIS WORKED FOR ME, after trying all the other solution ideas I could find in these forums (without success). I am using Adobe Digital Editions 4.5 and Windows 10.

Locate folder "My Digital Editions" (on my laptop), and delete all contents in the sub-folders (Annotations, Manifest, Restore (found empty), Tags, Thumbnails). Now I was able to open ADE and re-authorize ADE. I then synced my Kobo with the Kobo desktop program, which authorized my Kobo.

I was having the same issue using Windows 8.1.  I did find something that worked for me.  I uninstalled ADE 4.5 and then installed the Mozilla Firefox browser (Download Firefox — Free Web Browser).  (I am in no way endorsing this browser, just giving you something that worked for me.)  I used the new Firefox browser to download ADE 4.5 and now it works perfectly.  All the books I downloaded in the last year showed up.  Not sure why it worked, but it did.

Same issue, same efforts, same frustration. I am not going to hold my breath for Adobe to help. I last used ADE last month, it worked, but crashed. Now nothing.  I own many epub books - paid for - and want to use my investment. So I went searching for other solutions. Two solutions I found:

1. Freeware program Calibre. I have not tested all my books, but the 3 books I purchased tonight all opened fine. It seems you can export as well, I have not yet tried that. But looking good. (Recommended on Microsoft support forum).

2. Converter program Epubsoft. It allows you to save your purchased book to PDF, which you can then read in a PDF Reader, without getting frustrated by ADE.

Adobe is obviously too rich to care about paying customers, and don't worry about us dumping their software such as Lightroom, Photoshop, ADE and even Adobe Reader - all of which I have dumped recently. Good luck.

I have a similar problem: Adobe upgrade to 4.5.7 but I cannot get ADE to open any book.

My setup is W10 pro on a laptop.

Tried remove/reboot/reinstall -- did not help

This is a serious case of Adobe NOT CARING about its consumers.  I have tried contacting Adobe on all levels and I get nothing except 'use the forums' (because hopefully some poor beleaguered smuck like me will stumble on a fix) so Adobe doesn't have to fess up and fix it's bugs!  I am running a Windows 10 comp, and up until last week was working fine with Version 4.5.0.  Suddenly I was unable to open new purchases.  Google Play informed me I need the newest version.  Okay, download 4.5.7.  Suddenly everything stops.  It won't complete installation or even open.  At this point I plan to start letting the publishers know that Adobe is screwing up their sales by publishing crapware.  I won't spend money on books I cannot open!

ich habe eine Adope ID angelegt und immer wenn ich sie autizifieren soll sagt er geht nicht egal wo ich es versuche, ob Ebookreader oder Laptop. aber unterschiedliche Meldungen: am PC heißt es: Anmelde ID/Kennwort f. ausgew. ebsookanbieter  ist falsch. bitte erneut versuchen.

Same problem here on Windows 10. As of last night, when I try to open it there is some loading and then nothing happens. Monitoring the background processes, I see that it appears and then disappears a second later. Running as admin or reinstalling does not solve the problem. 3.0 opens but books don't work.