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Help us help you: include your environment details. We've made this easy for you. Use the Copy System Info button in Admin Panel › osAwesome › Diagnostics, then paste below.
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Hi
Theme Information: osTicket v1.15.1 // osTicket-1.15.1-Awesome-101
Software Environment: PHP 7.3.27 // MySQL 5.7.33 // Apache web server
The Attachment Inline Plugin dosen't word in this Version. Wit images is everything fine, but not with a PDF in the attachment of a ticket. PDF documents doesn't show in newest MacOS Safari browser. You will get always a grey screen and the browser crashes, so you can't click anything else. Is this a bug in newest osTicket Awesome? With newest Firefox or Google Chrome everything works fine. Thank's for your help.

And here a screenshot from the configuration menu of the attachment plugin:

Thank you for the report.
Please replace <span style="color: #008000;">/include/plugins/attachment_preview.phar</span> with this version.
You may need to then go to Admin Panel > Manage > Plugins and re-enable the Attachment Inline Plugin.
But either way, after that you should be good-to-go.
Hi stevland
Thanks for the quick help!
Uploaded your file to my server and reactivated the plugin. Unfortunately it didn't help, the problem is still there. I think it is a browser problem. Because on Google Chrome it works, but on Safari 14.0.3 for macOS it doesn't. If anyone else has any ideas, I would appreciate it. Otherwise, I'll try to work with Google Chrome, because everything works there.
Screenshot Safari with problem to show PDF:

Screenshot Google Chrome, everything works fine:

After updating the plugin, did you clear Safari's browser cache?
Unfortunately I do not have access to a Mac right now, so I can't test MacOS Safari.
But I did try it on an iPhone and a PDF did preview in iOS Safari, although the preview sometimes did not load right away until I refreshed the page.
If clearing Safari's cache doesn't help, try the SHIFT + O keyboard combination to view the same ticket in vanilla osTicket. Does the PDF preview display as expected over there?
(BTW I highly recommend using Chrome on MacOS anyway. I think it is a crime that Apple keep promoting Safari. Either they should accelerate its development, or they should abandon it. But that's my personal opinion, ymmv)