PNG is just fine and actually, they system will display an error if it doesn't like the file type.

So I'm back to not having a clue what is going wrong. 🙁
Hi guys,
I haven't been able to reproduce this in my demo installation, my own personal business installation, or on my testing server.
If either of you would be willing to let me access your installation, that would be extremely helpful.
If so, please submit this form with as much detail as possible. Otherwise, sorry but I am out of ideas.
I'm sorry that I have to ask you about this again after such a long time! But now do I have some time to develop our ticket system further.
I still have the problem that the logo is not printed, but I also noticed that avatars are not printed either. So I assume that the error is not with you but with an authorisation problem or PHP extension!
I host osTicket on a Synology RS and apart from the printing everything else works fine.
osTicket v1.17 // osTicket-1.17-Awesome-102
PHP 8.0.17 // MySQL 10.3.32 // Apache/2.4.51 (Unix) web server
PHP extensions: gd, imap, intl, ldap, mysqli, phar, zip, zlib

Greetings,
Markus
No logo printed and no avatars too, but each picture inserted in a ticket is.
Using the original osticket version intergrated in osticket awesome it doesn't print at all.
osTicket-Version: v1.17
Server-Software: Apache
MySQL-Version: 10.3.36
PHP-Version: 8.1.11
PHP-Extensions
gdlib
imap
xml
xml-dom
json
mbstring
phar
intl
fileinfo
zip
APCu
Zend
Opcache
# cat /etc/debian_version
10.13
Ok, I made a fresh reinstall in the root directory and stepped down to php 8.0 and all logos are printed, but not the avatars.