It makes sense that LR and the DNG Converter wouldn't support the same set of photos since both use the latest Adobe raw engine.
The A7III item on Adobe's supported camera list doesn't have an asterisk that indicates only uncompressed raw is supported, but their support for the camera was initially researched with one having firmware 0.01 not 1.01 so it's possible that type of compressed raw didn't exist with the original firmware so maybe they didn't know there was that option.
To verify that it is the file-format that is the problem, not that the photos are corrupted, try opening them in the Sony software that presumably ships with the camera, and do an export of all the photos to JPG.
If the Sony export to JPG succeeds for all the photos then the photo data is ok and it's Adobe that doesn't support something about some of the photos. If this is the situation then please upload a pair of photos, one that imports and one that doesn't, and someone *might* be able to pass them on to Adobe. Use dropbox or one drive or google drive and post a share link.
If the Sony export to JPG fails on the same photos that LR fails to import, then the photos are likely corrupted. Try another card reader or try plugging a cable directly into the camera to use it as a card reader--whichever you didn't do, initially, and see if the photos come across ok the second time. If so then the card-reader (if that's what you used initially) or the cable (to the camera if that's what you used initially) is the problem, and you should be able to use another reader or cable and get things to work.
If the Sony software does read and export the photos, then for the ones that don't work in LR, use the Sony software to export 16-bit TIFs (and with a ProPhotoRGB colorspace if that's an option) and import those TIFs into LR as substitutes for the raw files. Setting the shite-balance is best done from raw data so you might want to do that step in the Sony software if there is more than a little adjustment to do, but if the WB adjustment is going to be a slight tweak then it's probably fine to do that in LR from the TIF version of the photo.
Hi and thanks a lot for your complete answer.
I was about to reply to my own post. I could not even view the photos in Imaging edge since I read so many posts about Adobe programs compatibility problems. The conclusion is that somehow my SD card crashed in the middle of the photo shooting (after having tried it to my second camera today).
Maybe it was at the time I accidentally changed to compressed raw but I will never know, since I can do nothing with these files anymore. And I still suppose I changed it accidentally since I have never selected that option before and I saw it today selected.
Thanks again for your answer
> since I can do nothing with these files anymore
You might still be able to extract the embedded jpeg previews from the files using exiftool. Not as good as the raw but might allow you to save some images.
How can I do that? Can you provide additional info?
exiftool works from the command line so you need some familiarity with that. Examples on how to make exiftool do this are here: ExifTool example commands , here: Photo Phindings: How do I extract an embedded JPEG from a RAW file? here: Step by Step Preview Extraction from CR2. and many other places. The application is available here: https://sno.phy.queensu.ca/~phil/exiftool/ . It is quite complex and powerful and it can definitely extract previews but it is not easy to learn.
A prerequisite to extracting previews would be to separate the photos that are ok from the photos that are not ok into two separate folders because ExifTool will do things to all files in a folder and you don't need to extract previews from the ones that work ok in LR.
Assuming your running Windows:
1) Download ExifTool for Windows (currently exiftool-10.96.zip) from the link provided in the other reply:
2) Extract the contents of the ZIP to the folder with the bad ARW files.
3) Rename exiftool(-k).exe to exiftool.exe
4) Open a Command Prompt (Cortana search for CMD or Command Prompt).
5) Change Directories (Command Prompt CD) into the folder where your bad ARWs are.
6) Run exiftool in the folder using the following commandline:
exiftool.exe -b -PreviewImage -w %f_preview.jpg -r *.arw
This command means run exiftool, extracting the binary previewimage, writing to a JPG with the name of [filename]_preview.jpg, recurs into subfolders, do this for all the files with a ARW extension.
Here is an example of my running the command on a folder with two ARW files from an A7 III and A7R III:
You may get an error because you said the Sony Imaging Edge software wouldn't read the photos, either. If your Imaging Edge software is the current versions, 1.2, then it should be able to view the thumbnails, previews, and also edit raw data from the ARW files. If it cannot do any of these things then the files may be corrupted beyond repair.
If you want to upload one or more to dropbox or onedrive or googledrive or similar, someone else can take a look to see if anything is salvageable.
Here is the result of my running that EXIFTOOL command, earlier:
As you can see the extracted previews are not rotated and if you examine them in LR, they don't have any image metadata like what camera and what exposure settings were used. There is another exiftool commandline to copy such data from a raw to a jpg, but since these are corrupted, it is probably of no use.