"device not open" appears after saving a file in KWrite

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1

When I save kwrite /etc/default/grub in kwrite-25.04.2-1.fc42, I see:

QIODevice::write (QFile, “/etc/default/.grub.kate-swp”): device not open

Any ideas of why? It looks like it’s saved correctly.

Context

I was applying the undermentioned: