Here are some steps you can try to troubleshoot and resolve this issue:

1. Check for Firefox Updates Amazon Prime Video requires the latest version of Firefox to function correctly. Ensure that Firefox is up to date:

Open Firefox.

Click the three horizontal lines (hamburger menu) in the top-right corner.

Select Help > About Firefox.

If an update is available, Firefox will automatically download and install it.

2. Enable DRM Content Amazon Prime Video requires DRM (Digital Rights Management) support, which might be disabled in Firefox. Ensure that it's enabled:

In the Firefox address bar, type about:preferences#content and press Enter.

Scroll down to the Digital Rights Management (DRM) Content section.

Ensure the checkbox Play DRM-controlled content is checked.

3. Clear Cache and Cookies Sometimes, clearing the cache and cookies helps resolve issues with streaming services:

Click the hamburger menu > Settings.

Go to Privacy & Security.

Scroll down to Cookies and Site Data and click Clear Data.

Also, go to History > Clear Recent History, and choose a time range to clear.

4. Check for Hardware Acceleration Issues Firefox’s hardware acceleration might be causing issues with Prime Video. You can try turning it off:

In the Firefox address bar, type about:preferences#general and press Enter.

Scroll down to Performance.

Uncheck Use recommended performance settings.

Uncheck Use hardware acceleration when available.

Restart Firefox and see if Prime Video works.

5. Disable IPv6 Sometimes issues arise from network settings. Try disabling IPv6 to see if it helps:

In the Firefox address bar, type about:config and press Enter.

Accept the risk and continue.

Search for network.dns.disableIPv6.

Set the value to true (double-click the entry to toggle it).

6. Test in Safe Mode Firefox's Safe Mode disables add-ons and custom settings, which can help determine if a setting or extension is causing the issue:

Click the hamburger menu > Help > Restart with Add-ons Disabled.

Try using Amazon Prime Video again in Safe Mode.

If it works in Safe Mode, one of your add-ons or settings is likely the cause. You can try enabling them one at a time to identify the problematic one.

7. Check for Hardware or Software Conflicts If none of the above works, you could try checking if there’s an issue with your system's hardware or software that might be preventing Prime Video from loading on Firefox. This could include video drivers or system conflicts.

8. Try a New Firefox Profile If the issue persists, you might want to try creating a new Firefox profile to see if it's a profile-specific problem:

Type about:profiles in the Firefox address bar and press Enter.

Create a new profile and set it as default.

Try accessing Amazon Prime Video with this new profile.

Thuan27 -- thank you so much! I put Firefox in safe mode and that solved the problem. So it is one of my add-ons that's interfering with amazon prime. Again, thank you!