Windows 10 reached EOS (end of support) on October 14, 2025. For more information, see this article.

Avatar for Username

Rechercher dans l’assistance

Évitez les escroqueries à l’assistance. Nous ne vous demanderons jamais d’appeler ou d’envoyer un SMS à un numéro de téléphone ou de partager des informations personnelles. Veuillez signaler toute activité suspecte en utilisant l’option « Signaler un abus ».

En savoir plus

Ce sujet de discussion a été fermé et archivé. Veuillez poser une nouvelle question si vous avez besoin d’aide.

CORS error in Firefox incognito mode only

  • 2 réponses
  • 1 a ce problème
  • 485 vues
  • Dernière réponse par SuMo Bot

SuMo Bot
SuMo Bot
options supplémentaires

Hi there, I am working on a site with Segment API and need to load their JS on my site for it to work. Whats happening is, I get the following error: "Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://api.segment.io/v1/p. (Reason: CORS request did not succeed). Status code: (null)."

The weird part is, it happens only in Firefox incognito mode. It works on Chrome, Edge, Opera.

I am wondering if this is by design or if it is a bug.

Firefox version 98.0 (64-bit).

Hi there, I am working on a site with Segment API and need to load their JS on my site for it to work. Whats happening is, I get the following error: "Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://api.segment.io/v1/p. (Reason: CORS request did not succeed). Status code: (null)." The weird part is, it happens only in Firefox incognito mode. It works on Chrome, Edge, Opera. I am wondering if this is by design or if it is a bug. Firefox version 98.0 (64-bit).

Solution choisie

Is it a background request (fetch or XMLHttpRequest), or a regular script tag?

CORS background requests definitely require an Origin header. I wonder whether that is suppressed in private windows with some requests? You could inspect the headers in the Network panel of the Dev Tools. More info on that panel: https://developer.mozilla.org/docs/Tools/Network_Monitor

If it's a regular script tag, this could be due to Tracking Protection (by default, stricter in private windows) or an add-on that blocks analytics scripts. For Tracking Protection, click the shield icon at the left end of the address bar to check what is being blocked. With add-on blockers, the UI varies, but the toolbar button usually gives you an info panel.

Lire cette réponse dans son contexte 👍 0

Toutes les réponses (3)

jscher2000 - Support Volunteer
jscher2000 - Support Volunteer
  • Top 10 Contributor
options supplémentaires

Solution choisie

Is it a background request (fetch or XMLHttpRequest), or a regular script tag?

CORS background requests definitely require an Origin header. I wonder whether that is suppressed in private windows with some requests? You could inspect the headers in the Network panel of the Dev Tools. More info on that panel: https://developer.mozilla.org/docs/Tools/Network_Monitor

If it's a regular script tag, this could be due to Tracking Protection (by default, stricter in private windows) or an add-on that blocks analytics scripts. For Tracking Protection, click the shield icon at the left end of the address bar to check what is being blocked. With add-on blockers, the UI varies, but the toolbar button usually gives you an info panel.

SuMo Bot
SuMo Bot Auteur de la question
options supplémentaires

Hi @jscher2000, thanks for the response.

Disabling the Enhanced Tracking Protection worked.

SuMo Bot
SuMo Bot Auteur de la question
options supplémentaires

This question has been locked because the original author has deleted their account. While you can no longer post new replies, the existing content remains available for reference.