Mac will not open jpeg or ARW from Dropbox

[gregw822]

Just bought a new Macbook Pro. Photoshop 25 will not open files from Dropbox.

JPG gives this message: 

"because a JPEG marker segment length is too short (the file may be truncated or incomplete)."

ARW files give this message:

"Could not import the clipboard because Photoshop does not recognize this type of file"

What's ging here? In the 2nd case, I did use the Open command. Tere's nothing in the clipboard as far as I know.

[Kevin Stohlmeyer · Accepted solution]

@gregw822 have you tried transferring the assets out of Dropbox and then opening to confirm its not file corruption rather than a PS issue?

[gregw822]

Thanks. I can open. both file types if I use "Make available offline" in Dropbox. Plus, the preview images show up after "Make available...", but not for the files that haven't been "made available " . So....PS won't open files stored oline in DB. I suppose that means it's DB issue rather than a PS-25 problem?

[Kevin Stohlmeyer · Accepted solution]

Totally a Dropbox issue. The files are not accessible while synced in the cloud. Download to local always when working on them, save local, then put back into cloud storage when done. Actively attempting to work via network/cloud storage is a risk for corruption. 

[Conrad_C]

This is not an Adobe-specific issue, it can happen with any cloud synced service that offers removing synced items from local storage to save local space. Any file that is not made available offline is not fully downloaded, so when any application tries to open it, it’s incomplete. An incomplete file can produce I/O or End of File errors.

For example there’s a similar situation with Apple’s own iCloud Drive. If iCloud Drive content is set to be stored only on iCloud Drive instead of being synced with a local file, then what is left on Mac local storage is a “dataless” placeholder…the desktop says there is a file here, but there isn’t actually any data to open because it’s really up in the cloud. The file must be downloaded to be openable by local applications.

It’s possible that some applications are written to handle this so that it appears seamless and doesn’t produce an error. But the article I linked to above itself links to an Apple document that says:

“materializing a dataless file can take time if the file is large or there are poor network conditions. In such a scenario, the app may become unresponsive.”

In recent versions of macOS, Apple updated and standarized their cloud sync APIs and pretty much required all cloud services to update how they did things to maintain compatibility. So although I don’t technically know for sure, it’s possible that Dropbox now uses the Apple frameworks for this, especially since Dropbox is one of the cloud services that can be directly acceesible from the iOS Files app.

On the Adobe side, they may have prioritized working with their own Cloud Documents format which has some feature advantages over a typical cloud sync service. Cloud documents aren’t even synced to a local copy, they’re only temporarily cached when you work on them. You don’t have to manage whether any are downloaded, you just open them and the downloading is transparent. Those tend to work smoothly as long as there is a good network connection. For example, a Photoshop or Illustrator cloud document probably doesn’t produce the types of error you’re seeing.

[ExUSA]

And remember that an application can manage this. Dropbox has a compatibility API. So if Photoshop or Bridge had Dropbox support, the app would see the file and request that Dropbox sync it to the local drive. Photoshop would be blocked from opening the file and wouldn't throw an error unless the sync failed.

As it is, Photoshop has no way to talk to Dropbox and sync data. 

[ExUSA · Accepted solution]

You cannot work on files in Dropbox. They MUST be copied to your local drive and then opened.

[D Fosse]

...and that goes for any online storage/cloud, and also network storage. 

To be honest, I've seen so much file corruption in online storage services that I wouldn't dream of trusting them for archival purposes. I use dropbox only for making files available to clients.