Recently I've been having trouble packing my InDesign files, getting this message (translated from Swedish): "Failed to copy the necessary linked files" and the document is then not packed at all. Any suggestions what I can do about that? All links seem to be ok and the documents seem to be ok otherwise.
I'm moving your question to the InDesign forum
Check for illegal characters in file names. “/“ seems to be the biggest culprit. Very long file paths can also cause it.
I tried to pack the file in another destination folder, and (at least this time) it worked!