What das this mean: "invalid ..."

... When I just wanted to save the editing of a photo in the DNG (ctrl-s), I realised that the preview image had been recreated - and shows the original image without my edits!

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By @my cc

What you have done exactly. There's no need to save editings manually that have made in the develop section. This will be done automatically. Please describe more detailed and exactly the steps you've done.

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In between: what does this mean and what is the full text in this column (‘invalid ...’)?

 

By @my cc

It seems the LR can't get access to the drive where the images located. Could it be that you're using a external drive that was connected with another drive letter as on the import in LR?

For a better help we need also more infos about your system. Please provide a copy of your 'System Info'. This can be get from the LrC Help > System Info menu item. There's a copy button in the System Info dialog. Press this button and paste the info into your next forum post.

Your issue looks a lot like the following (unsolved)

• https://community.adobe.com/t5/lightroom-classic-discussions/invalid-path-representation-folders-in-lightroom/m-p/8777759

Inquiry, what hard drive is that folder in?

Hopefully not on a NAS

• https://community.adobe.com/t5/lightroom-classic-discussions/an-internal-error-has-occurred-invalid-path-error-while-finding-raw-folders-on-a-nas/m-p/13624232