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Forum Discussion
“Can't open the file because the file format/extension is not valid.” error on website/desktop app.
Hi,
I’m having a serious issue with Dropbox where many of my files appear in the correct folders on both my computer and on Dropbox.com, but none of those specific files will open. I receive errors like:
“Cannot open the file because the file format or file extension is not valid.”
Here’s what’s happening:
- I can see the file names and folder structure in Explorer.
- I can also see the same file names on Dropbox.com.
- But when I try to open any of these files (locally or on the web), they fail with format/extension errors.
- The files appear to be zero‑byte placeholders rather than real files.
- Most of my other files still exist on my second laptop, but the ones I urgently need do not.
- These missing files appear in Dropbox, but none of them open anywhere.
This all started after repeated issues with the Dropbox sync engine failing to start. Dropbox would install, but the app never launched, no tray icon appeared, and the sync engine seemed to be stuck in a crash loop. I believe this may have caused Dropbox to replace some of my original files with empty placeholder versions.
I need help determining:
- Whether Dropbox has older historical versions of these files stored internally.
- Whether a data recovery review is possible for these zero‑byte or corrupted placeholder files.
- Whether Dropbox can confirm if these files ever successfully uploaded before the sync engine failed.
These files are extremely important to me, and I’m hoping Dropbox Support can check server‑side logs or historical versions to see if recovery is possible.
Thank you for any help or escalation you can provide.
26 Replies
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Hannah, thanks for the reply.
Just to clarify: the Dropbox website does not open any files on any of my computers, so uploading files to the website wouldn’t help in this case.
Also, I can already open all of my existing files from the second computer (the HP). The only files I cannot open are the most recent ones, which do not appear on the HP at all and also won’t open on the Falcon or on Dropbox.com.
At this point, I’m mainly trying to get Dropbox running again on my primary computer (the Falcon), since the app does not launch. I'm looking for some help to do this properly.Don
Hi Hannah, thanks for the follow‑up.
I tried reinstalling the app exactly as you suggested. Then uninstalling and reinstalling. When I launch Dropbox, a window flashes for about a second with a message I can’t read, and then it closes immediately. After that, the Dropbox folder opens, but the Dropbox app itself never launches. There is no tray icon and no sync engine running.
None of the files in the Dropbox folder on the Falcon will open, and the behavior is exactly the same as before the reinstall.
Please advise on the next steps.
Dear Hannah,
Before I go any further with the Advanced Reinstall steps, I want to clarify a couple of things.
During the uninstall, Dropbox gave me an option to drag the Dropbox folder into the Recycle Bin, which I did, and then I emptied the Recycle Bin. I’m mentioning this because the Advanced Reinstall instructions say not to delete the main Dropbox folder, but the uninstaller itself prompted me to remove it.
Next, in the Registry Editor, I do not see a “Dropbox” folder directly under HKEY_LOCAL_MACHINE. However, under HKEY_LOCAL_MACHINE → SOFTWARE → WOW6432Node, I do see a Dropbox Update folder, and inside that are two folders: ClientState and ClientStateMedium.
Before I proceed, can you confirm exactly which registry folders I should delete?
I’d like to hear back from you before continuing.
— Don
- Hannah
Dropbox Community Moderator
Hi again, Don!
So, regarding the Dropbox folder, it should be okay that you deleted it; it's basically just to keep a copy locally just in case, but that's that.
As for the registry, you can delete the Dropbox Update folder from WOW6432Node, that's the correct one.
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