I've had Inkscape for a while but recently ran into a problem trying to save a new file. It says it cannot be saved in any format. I downloaded the newer Inkscape version, restarted computer and same issue. I have a Macbook Pro 2015. Any ideas?

Before proceeding further, I'd rest the preferences. https://inkscape.org/forums/questions/getting-back-to-square-one-and-starting-over-its-easy/

If that does not resolve the issue, please: 

1. Describe the specific steps you took, the result you expected, and the result that actually happened.
2. Describe your OS (your computer's Operating System: Mac/Windows/Linux/etc. & version).
3. Describe the version of Inkscape and the installer you used (the file you downloaded from the website: .msi/.exe/.zip/other ). 
4. Describe any special hardware being used, like tablet/stylus or multiple monitors.

I've got a Mac 12.6 Monterey, and Inkscape version 1.2.1. I had an older version of Inkscape and it stopped saving before I downloaded this version.

I updated my computer and reset the preferences on Inkscape but still cannot save a file. If I click the save icon it says no inkscape extension could be found. If I go to File>Save it just says document could not be saved. 

I found a workaround of sorts. If I open an existing document, change it and rename it, it will save.

I skimmed through the MacOS bugs and didn't see anything similar. https://gitlab.com/inkscape/inkscape/-/issues/?sort=priority&state=all&label_name%5B%5D=OS%3A%3AmacOS&first_page_size=103

Feel free to report a bug: https://inkscape.org/forums/beyond/how-to-report-bugs-or-request-new-features/