Description:
Upgrade LO yesterday.
Opened Calc and worked on a large spreadsheet with substantial LO Basic code that has been running for months. Without even noticing it, at some point I realised I the title bar had changed the extension from *.ods to "sheet.csv". However behaviour before I closed it was still that of a regular workbook, ie IDE was functional & loaded, my macros could be run, spreadsheet functions were operational, etc. Truly bizarre!

There was no indication of whether it was triggered by something I was doing in BASIC or if that was coincidental. Wasn't doing anything outrageous.

On closing, I was left with just the first sheet in the sheet.csv file, as would be expected. The previous save was still on disc and opened without apparent issue (so far!).

There was no error message or indication, no crash - this just happened without even noticing it until it was too late. I had not seen this error with previous versions of Calc using this same workbook or any other. I had been saving the file a few times every hour.

The recent LO upgrade was routine, done via Nala (apt). I run system update checks a few times a week, so the previous LO version was the latest in general release. 



Steps to Reproduce:
Not deliberately reproducible.Issue following upgrade to 24.8.2.1 suspected.

Actual Results:
[workbook].ods changed filename to sheet.csv in background
On save, csv file containing sheet #1 on disk. Previous save of [workbook].ods also found on disk and appears to be in good shape.

Expected Results:
No unprompted file conversion on the fly.


Reproducible: Didn't try


User Profile Reset: No

Additional Info:
Version: 24.8.2.1 (X86_64) / LibreOffice Community
Build ID: 0f794b6e29741098670a3b95d60478a65d05ef13
CPU threads: 12; OS: Linux 6.8; UI render: default; VCL: gtk3
Locale: en-AU (en_AU.UTF-8); UI: en-GB
Flatpak
Calc: threaded

OS Details:
OS details:
RELEASE=22
CODENAME=wilma
EDITION="Cinnamon"
DESCRIPTION="Linux Mint 22 Wilma"
DESKTOP=Gnome
TOOLKIT=GTK