Invalid resolution 0 dpi. Using 70 instead

Hi,
i have a new installation from Nextcloud 23.
I install the apps for fulltextsearch.
Now i want to create the first index. But always there is a warning with:

Invalid resolution 0 dpi. Using 70 instead

The Index is running on PDF Files, that i have scanned with 300dpi.

Now the first index take a long time to create.

Is this a Problem or can i fix this message?

Thx.
Regards
Hermann