If you have a bunch of missing (red) files that now live in the same directory, you can improve the "fix each path individually in the inspector" method by selecting (Cmd-click) all the files in one go. In the inspector you will see "several values":

Clicking the button in the Location drop-down list will lead to the directory selector - note that the prompt says "Select a folder containing ..." rather than "Select file and location".

Alex michaud
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