PDFs Don't Display Properly In Firefox 19

A PDF displayed in a Mozilla Firefox window may not display properly. Symptoms include:

• The display looks like a scanned image rather than with crisp text;

• Black or grey strips.

This may occur when using Firefox 19, which introduces its own PDF viewer.

To disable the Firefox 19 viewer:

1. Open Firefox.

2. Under Tools → Options, choose Advanced.

3. Next to Adobe Acrobat Document, choose Use Adobe Reader:
   

4. Click OK.

In later versions of Firefox (approximately 40 or greater):

1. Click the settings icon:
   

2. Under Options, Applications click Portable Document Format (PDF) and select Use Adobe Acrobat.

Alternatively:

1. Open Firefox.

2. In the address bar, enter about:config.

3. Click I'll be careful, I promise!

4. Search for pdfjs.

5. Double-click the line which reads pdfjs.disabled until Status is “user set” and Value is “true”.

To undo, repeat the steps but double-click so Status is “default”.