When you save and open files across a network or from removable media, many variables affect application performance. Consequently, some problems occur more frequently when you work across a network or from removable media than from a local hard disk. (Network-related problems include damaged files, denied access, or slow performance.) In these situations, Photoshop can return one of the following error messages:
- "Could not complete this operation because this file is in an unknown format."
- "Could not complete the request because the file is locked."
- "Could not save because of a disk error."
Note: Problems using Photoshop files across a network or from removable media can be intermittent or delayed.
Adobe Technical Support only supports using Photoshop and Adobe Bridge on a local hard disk. It's difficult to re-create or accurately identify network- and peripheral-configuration problems. Adobe Technical Support does, however, support using Photoshop with Adobe Drive and Adobe Version Cue. Version Cue is a file version management feature in Adobe Creative Suite that enables you to work with files in Version Cue workspaces on other computers. Photoshop CS4 supports Adobe Drive and Adobe Version Cue. Photoshop CS5 and later support Adobe Drive. (See "Recommended workflow" below for more information about Version Cue.)
Important: External hard drives are frequently used, especially by photographers, and should work with Photoshop without a problem. Testing against these drives by temporarily disabling them and working exclusively on an internal drive is appropriate. However, Adobe is not stating that there should be regular problems storing files and working with external (non-portable) hard disks.