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Long story short, this past week I had to do a fresh install of Windows 10, then recreate my old drive onto it. Everything has been going rather well until just now.
For some unknown reason, when I tried renaming image files moved from my phone, I can't use the format 5.26.26, today's date. Instead I get 5.26! The .26 dissapears!
Below is a screen shot showing the problem... note the 5.15 series. No .26. Sometimes if add a space after the date, it will work. BUT I don't WANT that space, and this NEVER happened in all the years I have had a computer.
I need renamed file-names to be accurate. Anyone have any ideas what is going on?
OK FOLKS, I think I fixed it!!!
After reading Mister AI's post, I started thinking and pondering...
I went to VIEW and SHOW FILE NAME EXTENTIONS, and BINGO, now the renaming works perfectly!!! I think the system now "sees" the .jpg and therefore accepts the date format I use.
Hey AI, I understand what you're saying, BUT I have been using the 5.26.26-style date format to rename image files for many, MANY years with NO problems. There has to be a setting somewhere that has changed.
More thoughts, maybe from a HUMAN?
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Hello Jonelle DeFelice,
I'm glad you got it sorted, and thanks for circling back to share the fix.
What you were running into is the "hidden extensions" trap — with extensions hidden, File Explorer was treating the last dot in 5.26.26 as the start of a new extension, so the trailing .26 got pushed into the (invisible) extension slot and the visible name showed up as 5.26. Turning on Show file name extensions makes the real .jpg visible, so when you type 5.26.26 Windows now correctly reads the whole thing as the filename and keeps .jpg as the extension untouched. That's why the date-style naming you've used for years suddenly behaves again.
I appreciate you posting the resolution — this is a common one to stumble into after a fresh install (the default flips extensions back to hidden), and your update will help the next person searching for the same symptom land on the answer quickly.
AI answer
Windows treats the last period in a file name as the separator between the name and the file extension. Anything after that final period is interpreted as the extension, not as part of the visible name.
When a name like 5.26.26 is entered for an image, File Explorer interprets:
5.26 as the file name.26 as the extensionBecause .26 is not a valid or recognized extension for that file type, Windows effectively hides or normalizes it, so the file appears as 5.26 in File Explorer. When a space is added (for example, 5.26.26 or 5.26.26 img), the last period is no longer directly followed by the extension characters, so the name is kept as typed.
To keep the full date visible and stable in the name, use one of these patterns that avoid a trailing period before the real extension:
2026-05-26_01 or 2026-05-26-015-26-265.26-265.26.26-1 (any extra character after the last period before the real extension)Or, if the image already has an extension like .jpg, explicitly include it when renaming, for example:
5.26.26.jpgIn that case, 5.26.26 is the file name and .jpg is the extension, so nothing disappears.
References: