I upgraded Fedora 33 MATE to Fedora 35 MATE a clean install. After installing all the necessary programs, I also noticed the lack of thumbnails in pdf. The culprit was MComix3, or rather its thumbnailer.
For myself, I did this - I edited the file /usr/share/thumbnailers/comicthumb.thumbnailer , removed the mention of pdf in it. Then you can delete the thumbnails in ~/.cache/thumbnails and reboot.
You can edit the file with the command “sed -i ‘s|;application/pdf||’ /usr/share/thumbnailers/comicthumb.thumbnailer” executed as root, but it’s better to look at the contents of the file first.
You can delete the comicthumb.thumbnailer, but then it takes too long to create thumbnails for cbX.
I’ve tried absolutely everything on this page, including reformatting my laptop, but nothing works. I do, however, have a couple of extras:
If I remove (rename) the .pdf extension, thumbnails and preview show flawlessly. If I put it back, it all goes back to normal.
My PDFs are not recognized as PDF by Gmail, linked or anything online. I tried repairing a pdf, but the repaired one doesn’t preview or open on those platforms.
I had a Lenovo and migrated all my files to my new HP Victus via a shared Public folder.
My files open on other computers.
New files don’t generate a preview either.
Here’s a file that cannot be displayed online, yet you can open it on your computer without problems: prueba de pdf.pdf - Google Drive
30+ years using Unix/Linux and this is my first question on a forum because I cannot solve a problem, so THANK you
What format was the shared folder – ext4, btrfs, ntfs, fat?
It could very easily be as simple as not having the proper selinux context for the transferred files.
To test if it is selinux related you could run sudo setenforce 0 then try accessing the pdf file. If it works then a relabel would likely be a good thing to relabel all with the proper selinux context. sudo touch /.autorelabel would create a file that tells the system to relabel the entire system on the next boot.
You also can run the file command and see what it tells you about the pdf files. file /path/to/pdfs/*.pdf will give you something like this
my-pdf-file_backup.pdf: PDF document, version 1.5 (zip deflate encoded)
my-pdf-file.pdf: PDF document, version 1.7 (zip deflate encoded)
I can see all my files, and edit them if I want to. I can send them via attachments and people can see them. If I upload it to g drive or LinkedIn, the files are not displayed at all (see the one I sent above), My issue here is the original problem someone had:
I cannot see the PDF thumbnails, except if I delete the .pdf extension. Look:
they are the same file, same content.
File types and pdf health is OK. SELinux, OK. It’s as if they had some sort of security bit turned on somewhere.
If I open them as a new user on my computer, I can see the generic pdf icon, but not the thumbnail, and I can see/upload them to online sites.
Both file systems are btrfs. My wife’s window PC can receive and see them. My old hp too (f35)
I added image/pdf to my evince thumbnailer and generated all thumbnails correctly. HOWEVER, now I have a problem that puzzles me: all my PDFs are MIMEtyped as image/pdf, except when I delete the pdf extension, which makes them “application/pdf”.
Any suggestions as to what could have happened? Fedora36, brand new OS.
SOLVED
My chrome had an app (photopea) that labeled the PDFs as image/pdf. I removed it, and everything is perfect. I didn’t need to edit evince thumbnailer after all. I’m happy.
