We're calling on all EU-based Mozillians with iOS or iPadOS devices to help us monitor Apple’s new browser choice screens. Join the effort to hold Big Tech to account!

Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

404 errors with version 91.0.1

  • 6 respostas
  • 1 has this problem
  • 1 view
  • Last reply by FredMcD

more options

Just updated Firefox from version 90.0.2 -> 91.0.1 on a Mac running OS 10.15.7.

I'm experiencing 404 errors of which do not occur in the previous version. Here's what the console shows...

Source map error: Error: request failed with status 404 Resource URL: https://MyWebsite.com/assets/vendor/bootstrap/css/bootstrap.min.css Source Map URL: bootstrap.min.css.map

I tried several things to try and isolate this issue, but all to no avail. The file does exist, and loads in the previous version of Firefox.

Any help would be greatly appreciate.

Just updated Firefox from version 90.0.2 -> 91.0.1 on a Mac running OS 10.15.7. I'm experiencing 404 errors of which do not occur in the previous version. Here's what the console shows... Source map error: Error: request failed with status 404 Resource URL: https://MyWebsite.com/assets/vendor/bootstrap/css/bootstrap.min.css Source Map URL: bootstrap.min.css.map I tried several things to try and isolate this issue, but all to no avail. The file does exist, and loads in the previous version of Firefox. Any help would be greatly appreciate.

Chosen solution

I called for more help.


cor-el said

This could be a problem with High Contrast Mode on Mac. See "New" in the release notes. Firefox now automatically enables High Contrast Mode when "Increase Contrast" is checked on MacOS in the Accessibility settings.

Make sure you allow pages to choose their own colors.

  • Settings -> General: Fonts & Colors -> Colors: "Override the colors specified by the page with my selections above"

Try "Never" if the default "Only with High Contrast themes" isn't working.

Ler a resposta no contexto 👍 0

All Replies (6)

more options

I tried https://mywebsite.com/assets/vendor/bootstrap/css/bootstrap.min.css and got:

Your connection is not secure

The owner of mywebsite.com has configured their website improperly. To protect your information from being stolen, Firefox has not connected to this website.


mywebsite.com uses an invalid security certificate.

The certificate is not trusted because it is self-signed. The certificate is not valid for the name mywebsite.com.

Error code: SEC_ERROR_UNKNOWN_ISSUER

more options

I should have been more clear.... I can not give you that actual url since it requires you to log in. I was just pointing out that it's a bootstrap website that works perfectly in the older version of Firefox.

Just about all websites I visit have issues with pages being displayed. You can see here with the attached screen capture from apple.com.

The background pic is the new version of Firefox, foreground pic is the older version. I just can't figure out why there's an issue with sites being rendered differently.

more options

I think there's more going on than my initial claim. Here's a site to visit: http://www.sandiegoadventurevans.com/index.html

For this site, I get no 404 errors, but the attached screen capture will show the difference between the two Firefox versions.

The new version (browser window on the right) clearly shows the CSS style for #faq element not being rendered correctly. Toggling this on/off does nothing to the displayed element in the page, even though it was loaded.

more options

Chosen Solution

I called for more help.


cor-el said

This could be a problem with High Contrast Mode on Mac. See "New" in the release notes. Firefox now automatically enables High Contrast Mode when "Increase Contrast" is checked on MacOS in the Accessibility settings.

Make sure you allow pages to choose their own colors.

  • Settings -> General: Fonts & Colors -> Colors: "Override the colors specified by the page with my selections above"

Try "Never" if the default "Only with High Contrast themes" isn't working.

more options

WOW.... this FIXED my problem, and never would have thought that this setting would cause drastic issues with page element styles.

I did have "Increase Contrast" checked in MacOS -> Accessibility settings.

Changing Settings -> General: Fonts & Colors -> Colors: "Override the colors specified by the page with my selections above" to Never fixed the issue.

Thank you very much for your time and efforts in helping me out!

more options

Glad to help. Safe Surfing.