Hi Tony, Firefox sometimes changes file extensions to match up with the content-type indicated by the server. If you change the file extension (without any conversion), you can test whether it is a renaming issue or something else. (You might need to set Windows to show all file extensions if you haven't already.)

Unfortunately, I can't find any built-in option to turn off the file extension renaming for media files (it can be turned off for non-media files such as documents).

There is a bug on file to look at this (#1734606), but any change is likely to come after the new year (Firefox 96 or later).

Until then... I have not been able to come up with any workarounds, but another support volunteer might have an idea.

Hi Tony, Firefox sometimes changes file extensions to match up with the content-type indicated by the server.

Thanks for the insight, Jefferson. In the case of the Audible audiobook, the download request returns these headers for the audiobook file:

Content-Type: audio/vnd.audible.aax
Content-Disposition: attachment; filename=AliceInWonderland_ep7.aax

Since the `Content-Type` indicated by the server is a custom MIME type that is only ever used by Audible AAX files, it seems Firefox shouldn't be changing the extension to MP4. Did something change in Firefox 93 that remapped the AAX content type to a different extension?

Additionally, the server is returning a `Content-Disposition` header that is explicitly suggesting the ".aax" extension; according to the documentation for that header, user agents like Firefox should be respecting that suggested filename.

Well, there is a bug on file already (#1734606) so I'm not sure what else to suggest.

Why is this marked solved. A bug report isn't a solution, is it?

Why is this marked solved. A bug report isn't a solution, is it?

The person who submits the question decides whether it is solved.

Anyway, until the bug is fixed, you need to manually edit the file extension to .aax so that it will open with Audible.

Are you certain this will work? I read on another question that manually editing the file extension doesn't solve the problem.

Are you certain this will work? I read on another question that manually editing the file extension doesn't solve the problem.

After the file is saved with the wrong extension, you can edit it to the correct extension -- Firefox is not modifying the actual file. If you are on Windows, make sure all extensions are showing so you don't end up with a file name like file.aax.mp4 (due to a hidden mp4 extension). See:

https://www.bleepingcomputer.com/tutorials/how-to-show-file-extensions-in-windows/

Thank you for the suggestion. I tried it.

The selected file has an extension (.aax) that is not recognized by windows media player, but the player may still be able to play it. Because the extension is unknown by the player you should be sure that the file comes from a trustworthy source. “ Then I have the option to try to play the file using Windows Media Player. This fails and I’m taken to a Windows *7* help file on Microsoft. (I’m on Windows 11)

Second question: Someone posted the fix for this might be available until after "the first of the year" but I didn't see what year was predicted. Today is 1/31/22. I just received notice of an update and hopefully downloaded it but I think it was a single fix. Help - About now says 96.0.3 3 (64 bit).

Thanks for reading my post.

Thank you for the suggestion. I tried it. The selected file has an extension (.aax) that is not recognized by windows media player, but the player may still be able to play it. Because the extension is unknown by the player you should be sure that the file comes from a trustworthy source. “ Then I have the option to try to play the file using Windows Media Player. This fails and I’m taken to a Windows *7* help file on Microsoft. (I’m on Windows 11)

It looks like Audible's Windows app is no longer available in the Microsoft Store. Another option would be to import the AAX files into iTunes (How can I import my Audible titles manually into iTunes?).

Otherwise, I noticed they have a Windows application called AudibleSync to convert their books to MP3: What is the AudibleSync app? If you are only interested in the audio track, that might be simplest.

Second question: Someone posted the fix for this might be available until after "the first of the year" but I didn't see what year was predicted. Today is 1/31/22. I just received notice of an update and hopefully downloaded it but I think it was a single fix. Help - About now says 96.0.3 3 (64 bit).

Sorry, no progress on the bug report yet.

Entering this on 2/10/22. I'm downloading Audible books through my Firebox browser to my MacBook Pro. I still use iTunes. I followed the earlier advice in late 2021 and changed .mp4 files to .aax files after download. The .mp4 files would complete and a black screen would appear in iTunes window. Changing the suffix by editing the file name would make the black screen go away and the newly downloaded book would function properly.

Then, a few days ago, I downloaded a book from Audible and it presented with .aax suffix. It went through the download cycle and at the conclusion the download "failed." I'm baffled. I should add that I upgraded to 97.0 but only after this happened. I tried again. The download still "failed."

I haven't tried switching to Chrome for downloads but I guess it's the next step. UPDATE: Tried Chrome immediately after posting this. It worked. Downloaded the .aax version.

Then, a few days ago, I downloaded a book from Audible and it presented with .aax suffix. It went through the download cycle and at the conclusion the download "failed." I'm baffled. I should add that I upgraded to 97.0 but only after this happened. I tried again. The download still "failed."

On the Downloads list, does Firefox give any explanation for the failure? If not, hmm, how can we figure that out. Perhaps check the Web Console for any error messages. Either:

• Windows/Linux: Ctrl+Shift+K
• Mac OS: Command+Alt+K

Thanks for the tip. Here's what I found but I have no idea if any of it relates to the Download failures (there have been four in a row - Firefox doesn't give a reason).

Content Security Policy: Ignoring “'unsafe-inline'” within script-src or style-src: nonce-source or hash-source specified Content Security Policy: Couldn’t process unknown directive ‘require-trusted-types-for’ Content Security Policy: Ignoring ‘x-frame-options’ because of ‘frame-ancestors’ directive. Content Security Policy: Ignoring “'unsafe-inline'” within script-src or style-src: nonce-source or hash-source specified Content Security Policy: Couldn’t process unknown directive ‘require-trusted-types-for’

As I said in an update, I switched to Chrome and downloaded several books successfully from my Audible account.

Thanks for the tip. Here's what I found but I have no idea if any of it relates to the Download failures (there have been four in a row - Firefox doesn't give a reason). Content Security Policy: Ignoring “'unsafe-inline'” within script-src or style-src: nonce-source or hash-source specified Content Security Policy: Couldn’t process unknown directive ‘require-trusted-types-for’ Content Security Policy: Ignoring ‘x-frame-options’ because of ‘frame-ancestors’ directive. Content Security Policy: Ignoring “'unsafe-inline'” within script-src or style-src: nonce-source or hash-source specified Content Security Policy: Couldn’t process unknown directive ‘require-trusted-types-for’

Hmm, those do not look relevant.

Firefox also has a global console called the Browser Console that open in its own window. Just being re-trying the download, open it using:

• Windows/Linux: Ctrl+Shift+J
• Mac OS: Command+Shift+J

Click the trash can at upper left to clear the clutter. Then switch over to Firefox and try the download again. Then switch back to the console to see what messages appear.