Decryption fails running iOS 14.2

It's not a Dropbox problem, its not a Microsoft problem, its an Apple problem that first started with iOS 4.1 so don't expect anyone other than Apple to fix it.  I just installed 14.2.1 on my phone and that did not fix it.  The version notes did not mention this issue so I didn't have my hopes up too much.

If you are trying to open a Microsoft Office file (Excel, Word, Powerpoint) that is password protected, you will need to have Microsoft Office or the individual apps (Excel, Word, Powerpoint) on your device.  I chose to install Microsoft Office instead of the individual apps just to cut down on the number of app icons on my screens.

If you want to test your devices ability to open a Microsoft password protected file without having Microsoft on your device, just email the encrypted file to yourself and try to open it from within the native Apple Mail app, do not save it anywhere on your device, just tap to open it. If Apple has fixed the issue, it will open otherwise you will get the blank white screen with the words Decryption Failed (null).

I am having the same issue today since updating to IOS 14.2

I am having the same issue even outside of dropbox.  It is happening with opening word documents attached to emails.

Right, we are all going to continue to have this issue until Apple releases a fix in a subsequent iOS update. In the meantime, just do as I wrote in this thread and you will be able to open MS Office files on your phone or iPad.

Hi. I had the same issue.

Problems solved: On an Apple iPhone 11 iOS 14.2, use the iOS Files App to open any file. Just enable the OneDrive and Dropbox Sliders under Locations in the Files App.

Hope it works for you guys.

Dear please share in detail, i have the same issue in my iPhone mail app while opening the password protected word or excel files.

Perhaps save the file first to a cloud drive or local.