Lock error trying to save a PCB - Software - KiCad.info Forums

(apologies if this is in the wrong category) I have been working on a PCB which saved fine yesterday. Made some minor tweaks today and on saving, I’m seeing the following: Can I get some advice on how to proceed? There’s only myself using the software and file system so I know it hasn’t been grabbed by someone else. Files exist on a OneDrive folder and definitely exist on the local filesystem. EDIT: I saved a copy (ok), closed and then tried re-opening the PCB and got this error

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