Steps to Reproduce:
1. Go to Control Panel - Server Administration - File Uploads
2. Under the "Documents and Media" heading change the "Allowed File Extensions" to ".jpg" and save
3. Go to Sites - Liferay - Documents and Media
4. Click Add - Multiple Documents
5. Upload a file other than a jpg
6. Assert error message is "Document names must end with one of the following extensions:" and does not contain the valid file extensions.
This is also reproducible in the Wiki portlet and when importing a LAR.