This solution is for all versions of Service Desk up to version 2018.1, where the issue was fixed.
Requires Access To:
Configuration Center access is required to complete these steps. SDaaS customers should open a support case to implement this solution.
The attempt to upload the attachment failed due to its filetype.
Situation may arise, where Service Desk disallows a certain file upload, even though that particular file extension already appears as whitelisted in Configuration Center file upload policy.
Known Problem 6869 - File Whitelist is case sensitive
Solution / Workaround:
For the whitelist to work on all files with different case variation of the extension, all allowed file extensions and their case types need to be added (8 entries per 3 character file extension). So for example to whitelist all .jpg files, you have to add all case variations of the extension to the whitelist, like this:
This was fixed in version 2018.1, where the whitelist is no longer case sensitive.