Recently, I began to notice many File records in Salesforce no longer displayed the file preview. When troubleshooting templates for Nintex Drawloop, this became a huge problem. Below is the resolution I stumbled upon:
- Navigate to Setup
- Go to the search box and enter ‘Regenerate Previews’
- Click on the ‘Regenerate Preview’ link
- Specify the Record ID of the File
- Click the ‘Generate Preview’ button
Note: This solution does not work for files over 25MB, password protected files, encrypted files, and file types not supported by Salesforce.