{"id":17679,"date":"2026-08-04T20:02:06","date_gmt":"2026-08-04T11:02:06","guid":{"rendered":"https:\/\/m365jp.net\/?p=17679"},"modified":"2026-08-04T20:07:10","modified_gmt":"2026-08-04T11:07:10","slug":"servicedegradation-cw1447067-microsoft-365-copilot-chat-users-may-be-unable-to-access-microsoft-copilot-chat-in-the-browser-and-may-encounter-a-400-request-header-error-3","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2026-08-04-servicedegradation-cw1447067-microsoft-365-copilot-chat-users-may-be-unable-to-access-microsoft-copilot-chat-in-the-browser-and-may-encounter-a-400-request-header-error-3","title":{"rendered":"[serviceDegradation] CW1447067 | Microsoft 365 Copilot Chat | Users may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error"},"content":{"rendered":"
\n
\n
\n\n\n\n
CW1447067 | Microsoft 365 Copilot Chat | Users may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error<\/th>\n<\/tr>\n<\/tbody>\n<\/table>\n
\n\n\n\n\n\n\n\n\n\n\n
Status<\/th>\nserviceDegradation<\/td>\n<\/tr>\n
Classification<\/th>\nincident<\/td>\n<\/tr>\n
User Impact<\/th>\nUsers may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error.<\/td>\n<\/tr>\n
Last Updated<\/th>\n08\/04\/2026 10:18:15<\/td>\n<\/tr>\n
Start Time<\/th>\n07\/31\/2026 20:00:00<\/td>\n<\/tr>\n
End Time<\/th>\n<\/td>\n<\/tr>\n
Latest Message<\/th>\nTitle: Users may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error <\/p>\n

User impact: Users may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error. <\/p>\n

More info: As a temporary workaround, affected users may be able to restore access to Microsoft Copilot Chat by clearing their browser cookies and then trying again. <\/p>\n

Current status: We’ve identified the root cause of the issue as a recent service change that affects the way browser authentication information is stored for Microsoft Copilot Chat. This can cause some browser requests to exceed expected limits, which may prevent users from accessing the service. We’re currently rolling out a fix and will share an update on deployment timeline in our next scheduled communication. <\/p>\n

Scope of impact: Impact is specific to some users attempting to access Microsoft Copilot Chat in the browser. <\/p>\n

Start time: Friday, July 31, 2026, at 8:00 PM UTC <\/p>\n

Root cause: A recent service change that affects the way browser authentication information is stored for Microsoft Copilot Chat. This can cause some browser requests to exceed expected limits, which may prevent users from accessing the service. <\/p>\n

Next update by: Tuesday, August 4, 2026, at 11:30 PM UTC<\/td>\n<\/tr>\n

Machine Translation<\/th>\n\u30bf\u30a4\u30c8\u30eb:\u30e6\u30fc\u30b6\u30fc\u306f\u30d6\u30e9\u30a6\u30b6\u4e0a\u3067Microsoft Copilot Chat\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u305a\u3001400\u30ea\u30af\u30a8\u30b9\u30c8\u30d8\u30c3\u30c0\u30fc\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3059\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059 <\/p>\n

\u30e6\u30fc\u30b6\u30fc\u3078\u306e\u5f71\u97ff:\u30e6\u30fc\u30b6\u30fc\u306f\u30d6\u30e9\u30a6\u30b6\u4e0a\u3067Microsoft Copilot Chat\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u305a\u3001400\u30ea\u30af\u30a8\u30b9\u30c8\u30d8\u30c3\u30c0\u30fc\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3059\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002 <\/p>\n

\u3055\u3089\u306b\u60c5\u5831:\u4e00\u6642\u7684\u306a\u56de\u907f\u7b56\u3068\u3057\u3066\u3001\u5f71\u97ff\u3092\u53d7\u3051\u305f\u30e6\u30fc\u30b6\u30fc\u306f\u30d6\u30e9\u30a6\u30b6\u306e\u30af\u30c3\u30ad\u30fc\u3092\u30af\u30ea\u30a2\u3057\u3066\u304b\u3089\u518d\u5ea6\u8a66\u307f\u308b\u3053\u3068\u3067Microsoft Copilot Chat\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3092\u56de\u5fa9\u3067\u304d\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002 <\/p>\n

\u73fe\u72b6:\u554f\u984c\u306e\u6839\u672c\u539f\u56e0\u306f\u3001Microsoft Copilot Chat\u306e\u30d6\u30e9\u30a6\u30b6\u8a8d\u8a3c\u60c5\u5831\u306e\u4fdd\u5b58\u65b9\u6cd5\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u6700\u8fd1\u306e\u30b5\u30fc\u30d3\u30b9\u5909\u66f4\u3067\u3042\u308b\u3053\u3068\u3092\u7279\u5b9a\u3057\u307e\u3057\u305f\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u4e00\u90e8\u306e\u30d6\u30e9\u30a6\u30b6\u30ea\u30af\u30a8\u30b9\u30c8\u304c\u4e88\u60f3\u4e0a\u9650\u3092\u8d85\u3048\u3001\u30e6\u30fc\u30b6\u30fc\u304c\u30b5\u30fc\u30d3\u30b9\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u306a\u304f\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u73fe\u5728\u4fee\u6b63\u3092\u5c55\u958b\u4e2d\u3067\u3001\u6b21\u56de\u306e\u30b9\u30b1\u30b8\u30e5\u30fc\u30eb\u3055\u308c\u305f\u9023\u7d61\u3067\u5c55\u958b\u30b9\u30b1\u30b8\u30e5\u30fc\u30eb\u306e\u66f4\u65b0\u3092\u304a\u4f1d\u3048\u3057\u307e\u3059\u3002 <\/p>\n

\u5f71\u97ff\u7bc4\u56f2:\u5f71\u97ff\u306f\u30d6\u30e9\u30a6\u30b6\u4e0a\u3067Microsoft Copilot Chat\u306b\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3059\u308b\u4e00\u90e8\u306e\u30e6\u30fc\u30b6\u30fc\u306b\u7279\u5316\u3057\u305f\u3082\u306e\u3067\u3059\u3002 <\/p>\n

\u958b\u59cb\u6642\u9593:2026\u5e747\u670831\u65e5\u91d1\u66dc\u65e5 21:00 UTC <\/p>\n

\u6839\u672c\u539f\u56e0:Microsoft Copilot Chat\u306e\u30d6\u30e9\u30a6\u30b6\u8a8d\u8a3c\u60c5\u5831\u306e\u4fdd\u5b58\u65b9\u6cd5\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u6700\u8fd1\u306e\u30b5\u30fc\u30d3\u30b9\u5909\u66f4\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u4e00\u90e8\u306e\u30d6\u30e9\u30a6\u30b6\u30ea\u30af\u30a8\u30b9\u30c8\u304c\u4e88\u60f3\u3055\u308c\u308b\u4e0a\u9650\u3092\u8d85\u3048\u3001\u30e6\u30fc\u30b6\u30fc\u304c\u30b5\u30fc\u30d3\u30b9\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u306a\u304f\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002 <\/p>\n

\u6b21\u56de\u66f4\u65b0:2026\u5e748\u67084\u65e5\u706b\u66dc\u65e5 23:30 UTC<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

CW1447067 | Microsoft 365 Copilot Chat | Users may be unable to access Microsoft Copilot Chat in the browser a […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[1],"tags":[],"class_list":["post-17679","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/17679","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/comments?post=17679"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/17679\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=17679"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=17679"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=17679"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}