{"id":17677,"date":"2026-08-04T17:01:30","date_gmt":"2026-08-04T08:01:30","guid":{"rendered":"https:\/\/m365jp.net\/?p=17677"},"modified":"2026-08-04T17:01:41","modified_gmt":"2026-08-04T08:01:41","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","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","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":"<div class=\"postie-post\">\n<div>\n<hr>\n<table id=\"section\">\n<tbody>\n<tr>\n<th width=\"95%\">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<hr>\n<table id=\"data\">\n<tbody>\n<tr>\n<th>Status<\/th>\n<td class=\"bad\">serviceDegradation<\/td>\n<\/tr>\n<tr>\n<th>Classification<\/th>\n<td>incident<\/td>\n<\/tr>\n<tr>\n<th>User Impact<\/th>\n<td>Users may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error.<\/td>\n<\/tr>\n<tr>\n<th>Last Updated<\/th>\n<td>08\/04\/2026 07:49:39<\/td>\n<\/tr>\n<tr>\n<th>Start Time<\/th>\n<td>07\/31\/2026 20:00:00<\/td>\n<\/tr>\n<tr>\n<th>End Time<\/th>\n<td><\/td>\n<\/tr>\n<tr>\n<th>Latest Message<\/th>\n<td>Title: Users may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error  <\/p>\n<p>  User impact: Users may be unable to access Microsoft Copilot Chat in the browser and may encounter a 400 Request Header error.  <\/p>\n<p>  More info: As a temporary workaround, some users may be able to mitigate the impact by clearing their browser cookies and then retrying access to Microsoft Copilot Chat.  <\/p>\n<p>  Current status: We&#8217;re reviewing service monitoring telemetry to isolate the source of the issue and establish a fix.  <\/p>\n<p>  Scope of impact: Impact is specific to some users attempting to access Microsoft Copilot Chat in the browser.  <\/p>\n<p>  Next update by: Tuesday, August 4, 2026, at 9:30 AM UTC<\/td>\n<\/tr>\n<tr>\n<th>Machine Translation<\/th>\n<td>\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<p>  \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<p>  \u3055\u3089\u306b\u60c5\u5831:\u4e00\u6642\u7684\u306a\u56de\u907f\u7b56\u3068\u3057\u3066\u3001\u4e00\u90e8\u306e\u30e6\u30fc\u30b6\u30fc\u306f\u30d6\u30e9\u30a6\u30b6\u306e\u30af\u30c3\u30ad\u30fc\u3092\u30af\u30ea\u30a2\u3057\u3001\u305d\u306e\u5f8cMicrosoft Copilot Chat\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3092\u518d\u8a66\u884c\u3059\u308b\u3053\u3068\u3067\u5f71\u97ff\u3092\u8efd\u6e1b\u3067\u304d\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002  <\/p>\n<p>  \u73fe\u72b6:\u554f\u984c\u306e\u539f\u56e0\u3092\u7279\u5b9a\u3057\u3001\u4fee\u6b63\u7b56\u3092\u78ba\u7acb\u3059\u308b\u305f\u3081\u306b\u30b5\u30fc\u30d3\u30b9\u76e3\u8996\u30c6\u30ec\u30e1\u30c8\u30ea\u3092\u898b\u76f4\u3057\u3066\u3044\u307e\u3059\u3002 <\/p>\n<p>  \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<p>  \u6b21\u56de\u66f4\u65b0:2026\u5e748\u67084\u65e5\u706b\u66dc\u65e5 \u5348\u524d9\u664230\u5206 UTC<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>CW1447067 | Microsoft 365 Copilot Chat | Users may be unable to access Microsoft Copilot Chat in the browser a 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