“Can't open the file because the file format/extension is not valid.” error on website/desktop app.

From the Start Menu, I launched the Dropbox App and this is the window that came up.  I know it’s small, but the tray window bar on the bottom right show that the Dropbox app is not running as there is no tray icon. The syne engine never starts.  I can see the files, but they do not open.

Next is a screen shot is from the Dropbox web. None of these will open from this window. However, on my other laptop I can open all of these EXCEPT the bottom file dated 1/27/2026. That file doesn’t even show up on my other computer. The reason I tried to relink/resync my primary computer was for this reason. Files were missing from the other computer. Something changed around the middle of January and anything that was added after around that date did not show up on computer 2.

It appears to me that during the attempted update, the files were corrupted.

As a side note: Yesterday with the help of a friend, I was finally able to recover at least the file names in my Dropbox folder. I had high hopes that they would open. When I double clicked a file, the first window that came up was that I could not open the file because I was out of memory and it asked me if I wanted to upgrade. I checked my records and confirmed that on June 07, 2025, I had paid $119.88 for an annual Dropbox Plus subscription. Because I was desperate to get that file back, I upgraded to the recommended subscription, which was the same price, $119.88. I received a confirmation email that I had been charged, restarted my computer but none of those files would open and gave me a format or extension not valid error message.

I do not know what kind of support I can expect with the Dropbox Plus subscription. I’m hoping the forum can help me.