{"id":17253,"date":"2026-07-11T01:01:56","date_gmt":"2026-07-10T16:01:56","guid":{"rendered":"https:\/\/m365jp.net\/?p=17253"},"modified":"2026-07-11T01:02:40","modified_gmt":"2026-07-10T16:02:40","slug":"servicedegradation-mo1420954-microsoft-365-suite-users-are-unable-to-access-microsoft-copilot-web-and-m365-cloud-microsoft","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2026-07-11-servicedegradation-mo1420954-microsoft-365-suite-users-are-unable-to-access-microsoft-copilot-web-and-m365-cloud-microsoft","title":{"rendered":"[serviceDegradation] MO1420954 | Microsoft 365 suite | Users are unable to access Microsoft Copilot web and m365.cloud.microsoft"},"content":{"rendered":"
\n
\n
\n\n\n\n
MO1420954 | Microsoft 365 suite | Users are unable to access Microsoft Copilot web and m365.cloud.microsoft<\/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 intermittently unable to access Copilot web and other pages that redirect to the m365.cloud.microsoft URL.<\/td>\n<\/tr>\n
Last Updated<\/th>\n07\/10\/2026 15:55:47<\/td>\n<\/tr>\n
Start Time<\/th>\n07\/09\/2026 01:27:54<\/td>\n<\/tr>\n
End Time<\/th>\n<\/td>\n<\/tr>\n
Latest Message<\/th>\nTitle: Unable to access Microsoft Copilot web and the m365.cloud.microsoft URL<\/p>\n

User impact: Users may be intermittently unable to access Copilot web and other pages that redirect to the m365.cloud.microsoft URL.<\/p>\n

More info: Access eventually times out with an error message stating, “Bad Request – Header Field Too Long. HTTP Error 400. A request field is too long.”<\/p>\n

The impacted URL is m365.cloud.microsoft and other URLs which redirect to this page, including but not limited to:
– office.com
– portal.microsoft.com <\/p>\n

Users may be using URLs such as office.com and the navigation Waffle to access M365 applications in the browser, such as Outlook. For this scenario, when the URL redirects to m365.cloud.microsoft they may experience impact, however, users can access M365 applications in the browser directly through the product\u2019s specific URL (eg outlook.office.com).<\/p>\n

As a potential workaround, users can use the desktop version of the Microsoft 365 applications. Additionally, users may experience temporary relief by refreshing the cache when trying to access through the browser.<\/p>\n

Current status: We\u2019re continuing to analyze and test the rollback of the previously mentioned change. Additionally, we\u2019re reviewing HTTP Archive format (HAR) files from impacted users to assist in identifying why specific chunks in the cookie size have increased above the allowed thresholds. In parallel, we\u2019re testing some redirect configuration paths to reproduce the issue internally and gather additional diagnostics to assist our investigation.<\/p>\n

Scope of impact: This issue could impact any user attempting to access Copilot web, or a URL which redirects to m365.cloud.microsoft.<\/p>\n

Next update by: Friday, July 10, 2026, at 4:00 PM UTC<\/td>\n<\/tr>\n

Machine Translation<\/th>\n\u30bf\u30a4\u30c8\u30eb:Microsoft Copilot web\u304a\u3088\u3073m365.cloud.microsoft\u306eURL\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u305b\u3093<\/p>\n

\u30e6\u30fc\u30b6\u30fc\u3078\u306e\u5f71\u97ff:\u30e6\u30fc\u30b6\u30fc\u306f\u65ad\u7d9a\u7684\u306bCopilot\u306e\u30a6\u30a7\u30d6\u3084m365.cloud.microsoft\u306eURL\u306b\u30ea\u30c0\u30a4\u30ec\u30af\u30c8\u3055\u308c\u308b\u4ed6\u306e\u30da\u30fc\u30b8\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u306a\u3044\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n

\u8ffd\u52a0\u60c5\u5831:\u30a2\u30af\u30bb\u30b9\u306f\u6700\u7d42\u7684\u306b\u30bf\u30a4\u30e0\u30a2\u30a6\u30c8\u3057\u3001\u300c\u60aa\u3044\u30ea\u30af\u30a8\u30b9\u30c8 – \u30d8\u30c3\u30c0\u30fc\u30d5\u30a3\u30fc\u30eb\u30c9\u304c\u9577\u3059\u304e\u308b\u300d\u3068\u3044\u3046\u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u304c\u8868\u793a\u3055\u308c\u307e\u3059\u3002HTTP\u30a8\u30e9\u30fc400\u3002\u30ea\u30af\u30a8\u30b9\u30c8\u30d5\u30a3\u30fc\u30eb\u30c9\u306f\u9577\u3059\u304e\u308b\u3002\u300d<\/p>\n

\u5f71\u97ff\u3092\u53d7\u3051\u308bURL\u306fm365.cloud.microsoft\u3067\u3042\u308a\u3001\u3053\u306e\u30da\u30fc\u30b8\u306b\u30ea\u30c0\u30a4\u30ec\u30af\u30c8\u3055\u308c\u308b\u4ed6\u306eURL\u306b\u306f\u4ee5\u4e0b\u304c\u542b\u307e\u308c\u307e\u3059\u304c\u3001\u3053\u308c\u3089\u306b\u9650\u5b9a\u3055\u308c\u307e\u305b\u3093\u3002
– office.com
– portal.microsoft.com<\/p>\n

\u30e6\u30fc\u30b6\u30fc\u306f office.com \u3084\u30ca\u30d3\u30b2\u30fc\u30b7\u30e7\u30f3\u306eWaffle\u306a\u3069\u306eURL\u3092\u4f7f\u3063\u3066\u3001Outlook\u306a\u3069\u306e\u30d6\u30e9\u30a6\u30b6\u5185\u306eM365\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306b\u30a2\u30af\u30bb\u30b9\u3057\u3066\u3044\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u306e\u5834\u5408\u3001URL\u304cm365.cloud.microsoft\u306b\u30ea\u30c0\u30a4\u30ec\u30af\u30c8\u3055\u308c\u308b\u3068\u5f71\u97ff\u3092\u53d7\u3051\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u304c\u3001\u30e6\u30fc\u30b6\u30fc\u306f\u88fd\u54c1\u306e\u7279\u5b9aURL(\u4f8b:outlook.office.com)\u3092\u901a\u3058\u3066\u30d6\u30e9\u30a6\u30b6\u5185\u306eM365\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306b\u76f4\u63a5\u30a2\u30af\u30bb\u30b9\u3067\u304d\u307e\u3059\u3002<\/p>\n

\u56de\u907f\u7b56\u3068\u3057\u3066\u3001\u30e6\u30fc\u30b6\u30fc\u306fMicrosoft 365\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u30c7\u30b9\u30af\u30c8\u30c3\u30d7\u7248\u3092\u4f7f\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3055\u3089\u306b\u3001\u30d6\u30e9\u30a6\u30b6\u7d4c\u7531\u3067\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3059\u308b\u969b\u306b\u30ad\u30e3\u30c3\u30b7\u30e5\u3092\u66f4\u65b0\u3059\u308b\u3053\u3068\u3067\u4e00\u6642\u7684\u306a\u5b89\u5fc3\u611f\u3092\u5f97\u308b\u3053\u3068\u3082\u3042\u308a\u307e\u3059\u3002<\/p>\n

\u73fe\u72b6:\u524d\u8ff0\u306e\u5909\u66f4\u306e\u30ed\u30fc\u30eb\u30d0\u30c3\u30af\u306e\u5206\u6790\u3068\u30c6\u30b9\u30c8\u3092\u7d99\u7d9a\u3057\u3066\u3044\u307e\u3059\u3002\u3055\u3089\u306b\u3001\u5f71\u97ff\u3092\u53d7\u3051\u305f\u30e6\u30fc\u30b6\u30fc\u306eHTTP Archive Format(HAR)\u30d5\u30a1\u30a4\u30eb\u3082\u30ec\u30d3\u30e5\u30fc\u3057\u3001\u30af\u30c3\u30ad\u30fc\u30b5\u30a4\u30ba\u306e\u7279\u5b9a\u306e\u30c1\u30e3\u30f3\u30af\u304c\u8a31\u5bb9\u95be\u5024\u3092\u8d85\u3048\u305f\u7406\u7531\u3092\u7279\u5b9a\u3059\u308b\u306e\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002\u540c\u6642\u306b\u3001\u5185\u90e8\u3067\u554f\u984c\u3092\u518d\u73fe\u3059\u308b\u305f\u3081\u306b\u30ea\u30c0\u30a4\u30ec\u30af\u30c8\u8a2d\u5b9a\u30d1\u30b9\u3092\u30c6\u30b9\u30c8\u3057\u3001\u8abf\u67fb\u3092\u652f\u63f4\u3059\u308b\u305f\u3081\u306e\u8ffd\u52a0\u306e\u8a3a\u65ad\u30c7\u30fc\u30bf\u3092\u96c6\u3081\u3066\u3044\u307e\u3059\u3002<\/p>\n

\u5f71\u97ff\u7bc4\u56f2:\u3053\u306e\u554f\u984c\u306f\u3001Copilot\u306e\u30a6\u30a7\u30d6\u306b\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3059\u308b\u30e6\u30fc\u30b6\u30fc\u3084\u3001m365.cloud.microsoft\u306b\u30ea\u30c0\u30a4\u30ec\u30af\u30c8\u3055\u308c\u308bURL\u306b\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3059\u308b\u3059\u3079\u3066\u306e\u30e6\u30fc\u30b6\u30fc\u306b\u5f71\u97ff\u3092\u53ca\u307c\u3059\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n

\u6b21\u56de\u66f4\u65b0:2026\u5e747\u670810\u65e5\u91d1\u66dc\u65e5 \u5348\u5f8c4:00 UTC<\/td>\n<\/tr>\n<\/tbody>\n<\/table><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"

MO1420954 | Microsoft 365 suite | Users are unable to access Microsoft Copilot web and m365.cloud.microsoft St […]<\/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-17253","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/17253","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=17253"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/17253\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=17253"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=17253"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=17253"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}