I have a dialog box telling the user to upload new pictures, but if one picture already exists there is a notification telling the user this information and he have to remove it himself. The problem is that all uploaded pictures have a green checking-sign, like so:

enter image description here

This of course has to be improved. There should at least not be a green check-sign if the picture already exists.

enter image description here

But is there a way to prevent the error? I don’t want the user to make the error in the first place, and absolutely not having to correct it himself.

  • It isn't clear from the question what the user might want in this situation: Cancel the upload because it is already done? Upload the second picture with a deduplicated name? Replace the previous picture? More information on the use case would help here.
    – user31143
    Apr 25, 2016 at 11:46
  • It is also not clear what counts as "already exists"? Is this if there is a duplicate file name only? Or are you checking image dimensions, bytes and/or a checksum?
    – scunliffe
    Apr 26, 2016 at 12:10

2 Answers 2


How about the approach in Windows and OS X when copying files/folders?

Validate before the file is uploaded, and give the option to the user what they want to do with duplicates: replace, skip, or rename/keep both.

Windows 8

Windows 8



  • Great reply. This would both give the user a "positive" kind of feedback, while keeping an easy and user-friendly UI.
    – MJB
    Apr 25, 2016 at 12:33

In general, in any validation process, the validation should be taken before the action performed. So, you have to check for file existence before uploading process, then cancel the upload for the existing file and notify the uploader.

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