Update file locations
The file locations currently stored in the database will be pointing to the production file share. These should be updated to point to the file share locations for test. These settings should be updated in System Settings > File locations.
Check also the WebDAV file settings. If you have secure WebDAV you probably need to update them too.
If you use Mobile Apps also check your icon location in Apps > Mobile Settings.
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To ensure you have the correct templates, copy the templates from the PROD environment to the TST/ACC environment.