HI, Love Directory Opus, but recently have run into a flaw. When I move files (often, not always) between folders, the file extension disappears causing the file to have to be renamed with the proper extension. Seems like this has only started to occur recently. Is this a known bug. Is there a …

The type column saying "XYZ File" means "XYZ" wasn't recognised as an extension in the registry. So it could well be a strange, hard to see character (e.g. a zero-width space) being inserted into the extension somehow, as PassThePeas suggests. (It could be something else entirely as well, of course…

[image] Leo: The type column saying "XYZ File" means "XYZ" wasn't recognised as an extension in the registry. I see the point you and PtP make. The name given for the extension in the first screen shot is not fleshed out to 'Microsoft Office Excel...." (after lookup in HKEY_Classes_Root), bu…

[image] DaveM: Well, would that be the case? Does the associative table in Windows' HKEY_Classes_Root of all the recognized extensions have regexs that would support such variability? From my use of those, it is a strictly character matching function without any bells: a type of .xlsx is precede…

[image] DaveM: Wonder what the filename looks like if dumped into a hex editor? Same here :slight_smile: [image] DaveM: This implies that another mechanism is being used to query the contents of the file to determine that it looks like an Excel file, despite its hidden/non-existent exten…

[image] DaveM: This implies that another mechanism is being used to query the contents of the file to determine that it looks like an Excel file, despite its hidden/non-existent extension. Well when stumped, ask a guy with terabytes readily at hand: There are several subtle reasons why an …

Please don't post AI slop to our forum. :slight_smile: [image] Please do not use AI to create posts on this forum light_bulbOpus FAQs The forum's official policy is that "AI" such as ChatGPT should not be used to create posts, other than when used as a machine…

[image] Leo: Please don't post AI slop That seems a bit harsh to call what Gemini AI found 'slop'. I thought it was useful to learn about magic numbers used to id file types, regardless of file extension. It answers a question from PTP about file identification. If you think that it moves …

It's slop because it's irrelevant, doesn't add to the discussion, and contradicts things you've been told by people who actually know how it works.

Points 2-4 seem quite plausible. I strongly challenge the first point though (which does not seem to be backed up by any source). FWIW, this very day again, I was trying to do stuff around Native Instruments files, and Gemini freely told me that .nicnt files were in fact XML files that I could pars…

Would it be more palatable if I had used the Wiki-PediA reference, given by Gemini AI, to an article discussing how magic (file) numbers help to identify file types, even ones lacking a filename extension? Agreeing, as it does, with what Jon alluded to earlier in the discussion. Is Gemini AI corre…

File Ext Disappears When I Move Files

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Leo March 7, 2026, 7:48pm 17

Please don't post AI slop to our forum.