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Dropbox desktop on Mac corrupts files -- downloading from web is fine

cfarley137

I've got a Mac with a small SSD -- smaller than my Dropbox account. So I use "Selective Sync" to keep most of my large photo library in the cloud. When I need some files, I enable "Selective Sync" and allow that directory to sync to my Mac.

Recently, my photographs (JPEGS) have become corrupt when I sync them with Selective Sync. When I try to open files that have recently synced, the Mac indicates that the file "may be damaged or use a format that Preview doesn't recognize".

If I go to the Dropbox website and download the file there, everything works fine.

If I run a diff on the files I download from the website and the files that sync automatically, they are, in fact, different.

I am using Dropbox v82.4.155

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Accepted answers

akariv

In case anyone is interested in the solution for this problem -

Files were erroneously marked as 'online only', a smart-sync feature (even though smart-sync wasn't even enabled).

I had to enable it and mark the files as 'local' (via the context menu), which solved the problem.

hth

All comments

Fiona

Thanks for the detailed description of your issue @cfarley137. Welcome to Dropbox Community.

Are you trying to open the files locally while they are still syncing maybe? :thinking: If you have selected the files to download locally in your Selective Sync list and the process is not completed/app is not "Up to date" then the files will not be able to open.

Please add a screenshot of the error messages you are getting and the differences you see to the files after you download them.

Finally, I would also like know if these files have been edited via a third party app recently and when this problem started, as well as the version of your OS on this device.

Dropbox cannot change the filetype or corrupt a file. I strongly suggest to read more about corrupted/renamed files from our help center to make sure the changes are not related to ransomware: https://help.dropbox.com/accounts-billing/security/ransomware-recovery

No worries. If this is the case we can help. However, the fact that the files are functional online is encouraging!

Once I see what you see I will be able to advise further. Thanks!

cfarley137

I am not trying to open the files when they are still syncing. The Dropbox widget says "Up To Date".
I am using Dropbox v82.4.155 on MacOs 10.14.6
The JPEGs have not been recently edited at all. No modifications to the files since initially syncing to Dropbox.
I noticed this problem for the first time within the past week. I often use Selective Sync to restore my archived photographs, and have never had this problem before.
The file that syncs and the file that I download from the Dropbox website definitely differ. The file sizes are the same, however the command line utility "diff" shows that the files differ. Also, the files have different MD5 hashes. Finally, the file I download from the Dropbox website behaves normally (I can view the JPEG in Preview and other apps), while the other version is not a valid JPEG.
Here is the error message I get when I try and open any JPEG file that syncs via the Dropbox app:

cfarley137

I used the program vbindiff to examine the files. The difference is obvious. The Dropbox app is creating a file with the same name, extension, and file size. However the contents of the file are completely empty. Every byte is "00", whereas the files I dowload from Dropbox.com have lots of data in them. It is as if the Dropbox app is allocating the space for the files, but never actually syncs the contents of the files.

akariv

I'm experiencing the exact same problem (selective sync, zero-ed out files).

Client version: v84.4.170

OS version: 10.14.6

akariv

In case anyone is interested in the solution for this problem -

Files were erroneously marked as 'online only', a smart-sync feature (even though smart-sync wasn't even enabled).

I had to enable it and mark the files as 'local' (via the context menu), which solved the problem.

hth

Fiona

Hello there!

Being opted-out of the system extension may also mean that if you have existing placeholder files (files with the grey cloud icon) and try to open them by double-clicking the file, you may see an error. You can ultimately open these files by right-clicking on them and choosing to make the file "local" as you correctly mentioned @akariv.

Just confirming what you said here is accurate. :white_check_mark:

Thanks for posting your solution.

clawback

I had the same problem and akariv's solution worked for me. It is possible to set a whole folder to local so it is quick to fix.