UDDEIM attachment (image) is downloadable, but can´t open image

User can send attachments with the uddeIM PMS. The download of the attachment (for example a jpg picture) is possible and the download process works fine. But I can´t open this file/image with the computer. It looks like a broken file.

Enclosed you can find such a file/image.

Any ideas what can cause this "destroyed" file?

I had similar problem - I think the cause is running PHP 7.3 or above

If you are running 7.3 see this thread www.joomlapolis.com/forum/25-uddeim-plugin-and-component/242085-warning-udeim - contains links ot 2 other threads that document patches. Apply these and then try again

Thank you for your idea.
We used PHP 7.2.22

But nevertheless I upgrades PHP to 7.3.10 and changed the files admin.shared.php, bbparser.php and attachment.php as described. But the attachments are still "destroyed" after download and I can´t open them.

Are you getting any error message - either on screen or in the php error log

Yes, two warnings regards uddeim:

Warning: Declaration of getuddeimTab::sendUserPMS($toid, $fromid, $subject, $message, $systemGenerated = false, $escaped = false) should be compatible with cbPMSHandler::sendUserPMS($toUserId, $fromUserId, $subject, $message, $systemGenerated = false, $fromName = NULL, $fromEmail = NULL) in /htdocs/jaii/components/com_comprofiler/plugin/user/plug_privatemessagingsystem(uddeimpms)/pms.uddeim.php on line 0

Warning: count(): Parameter must be an array or an object that implements Countable in /htdocs/jaii/components/com_uddeim/inbox.php on line 481

Sorry, I'm not sure what the problem is