I replaced my old camera with CR2 raw format a while ago with a new one (Canon EOS R6) with CR3. As soon as I shot the first pictures with it I had the problem that they could not be opened in Photoshop CS6. An upgrade to a newer Photoshop version is out of the question for me, because I don't want to sign up for a subscription and the "old" functions are quite sufficient for me.
After a short research I came across the following post in the Adobe Community and since then I use the DNG converter.
The latest version of Camera Raw that works with CS6 is 9.1.1, so although you seem to have been able to install version 12.4, it won't work with CS6, which is most likely still using 9.1.1 (or older).
The workaround is to use the free Adobe DNG converter, which will convert (copies of) your CR3 files to DNG files, that can be opened in 9.1.1/CS6.
However, I still keep all CR3 files just for safety because the question arises: is the conversion lossless? Do I have any disadvantages by the conversion or could I delete the original files without hesitation? My NAS still has enough free space, but at some point I'll have to choose between resolving the redundancies or investing in more storage.
I found this question, which suggests that there is no loss to the image, but possibly to the metadata. However, since this post is already 12 years old and refers to the Sony ARW format, I am unsure if this still applies to newer Canon formats.
