{"id":18984,"date":"2026-10-15T06:03:05","date_gmt":"2026-10-14T21:03:05","guid":{"rendered":"https:\/\/m365jp.net\/?p=18984"},"modified":"2026-10-15T06:06:06","modified_gmt":"2026-10-14T21:06:06","slug":"servicedegradation-ex1507783-exchange-online-some-users-mailbox-syncs-may-fail-with-an-error-in-exchange-online","status":"publish","type":"post","link":"https:\/\/m365jp.net\/index.php\/2026-10-15-servicedegradation-ex1507783-exchange-online-some-users-mailbox-syncs-may-fail-with-an-error-in-exchange-online","title":{"rendered":"[serviceDegradation] EX1507783 | Exchange Online | Some users’ mailbox syncs may fail with an error in Exchange Online"},"content":{"rendered":"
\n
\n
\n\n\n\n
EX1507783 | Exchange Online | Some users’ mailbox syncs may fail with an error in Exchange Online<\/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’ mailbox syncs may fail with an error in Exchange Online.<\/td>\n<\/tr>\n
Last Updated<\/th>\n10\/14\/2026 20:51:53<\/td>\n<\/tr>\n
Start Time<\/th>\n10\/14\/2026 18:50:39<\/td>\n<\/tr>\n
End Time<\/th>\n<\/td>\n<\/tr>\n
Latest Message<\/th>\nTitle: Some users’ mailbox syncs may fail with an error in Exchange Online <\/p>\n

User impact: Users’ mailbox syncs may fail with an error in Exchange Online. <\/p>\n

More info: Users see the following error message in Microsoft Graph: “HTTP 400 — Operation not allowed — Operation on Non IPM Subtree forbidden.” <\/p>\n

Current status: We’ve identified a recent code change made to specific mailbox APIs which is resulting in the error messages seen in Microsoft Graph when these apps access non-Interpersonal Messaging (IPM) mailboxes. We’re reverting this change to verify that it’s the source of this issue and to fully remediate impact. <\/p>\n

Scope of impact: This issue may affect some users’ mailbox syncs, specifically for customers using apps that access non-Interpersonal Messaging (IPM) mailboxes through Microsoft Graph, which returns an error code in Exchange Online. This information may be updated as our investigation continues. <\/p>\n

Next update by: Wednesday, October 14, 2026, at 10:30 PM UTC<\/td>\n<\/tr>\n

Machine Translation<\/th>\n\u30bf\u30a4\u30c8\u30eb:\u4e00\u90e8\u306e\u30e6\u30fc\u30b6\u30fc\u306e\u30e1\u30fc\u30eb\u30dc\u30c3\u30af\u30b9\u540c\u671f\u304cExchange Online\u3067\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3057\u3001\u5931\u6557\u3059\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059 <\/p>\n

\u30e6\u30fc\u30b6\u30fc\u3078\u306e\u5f71\u97ff:Exchange Online\u3067\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3057\u3001\u30e6\u30fc\u30b6\u30fc\u306e\u30e1\u30fc\u30eb\u30dc\u30c3\u30af\u30b9\u540c\u671f\u304c\u5931\u6557\u3059\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002 <\/p>\n

\u8a73\u7d30\u60c5\u5831:Microsoft Graph\u3067\u4ee5\u4e0b\u306e\u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u304c\u8868\u793a\u3055\u308c\u307e\u3059:\u300cHTTP 400 — \u64cd\u4f5c\u306f\u8a31\u53ef\u3055\u308c\u307e\u305b\u3093 — \u975eIPM\u30b5\u30d6\u30c4\u30ea\u30fc\u4e0a\u306e\u64cd\u4f5c\u306f\u7981\u6b62\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u300d <\/p>\n

\u73fe\u72b6:\u7279\u5b9a\u306e\u30e1\u30fc\u30eb\u30dc\u30c3\u30af\u30b9API\u306b\u5bfe\u3057\u3066\u6700\u8fd1\u30b3\u30fc\u30c9\u5909\u66f4\u304c\u884c\u308f\u308c\u305f\u3053\u3068\u3092\u78ba\u8a8d\u3057\u307e\u3057\u305f\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u3053\u308c\u3089\u306e\u30a2\u30d7\u30ea\u304c\u975e\u5bfe\u4eba\u30e1\u30c3\u30bb\u30fc\u30b8\u30f3\u30b0(IPM)\u30e1\u30fc\u30eb\u30dc\u30c3\u30af\u30b9\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u969b\u306bMicrosoft Graph\u306b\u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u304c\u8868\u793a\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u3053\u306e\u5909\u66f4\u3092\u5143\u306b\u623b\u3057\u3001\u554f\u984c\u306e\u539f\u56e0\u3067\u3042\u308b\u3053\u3068\u3092\u78ba\u8a8d\u3057\u3001\u5f71\u97ff\u3092\u5b8c\u5168\u306b\u4fee\u6b63\u3059\u308b\u305f\u3081\u306b\u884c\u3044\u307e\u3059\u3002 <\/p>\n

\u5f71\u97ff\u7bc4\u56f2:\u3053\u306e\u554f\u984c\u306f\u3001Microsoft Graph\u3092\u901a\u3058\u3066\u975e\u5bfe\u4eba\u30e1\u30c3\u30bb\u30fc\u30b8\u30f3\u30b0(IPM)\u30e1\u30fc\u30eb\u30dc\u30c3\u30af\u30b9\u306b\u30a2\u30af\u30bb\u30b9\u3059\u308b\u30a2\u30d7\u30ea\u3092\u4f7f\u7528\u3057\u3066\u3044\u308b\u4e00\u90e8\u306e\u30e6\u30fc\u30b6\u30fc\u306e\u30e1\u30fc\u30eb\u30dc\u30c3\u30af\u30b9\u540c\u671f\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u306e\u30a2\u30d7\u30ea\u306fExchange Online\u3067\u30a8\u30e9\u30fc\u30b3\u30fc\u30c9\u3092\u8fd4\u3057\u307e\u3059\u3002\u8abf\u67fb\u304c\u9032\u3080\u306b\u3064\u308c\u3066\u3001\u3053\u306e\u60c5\u5831\u306f\u66f4\u65b0\u3055\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002 <\/p>\n

\u6b21\u56de\u66f4\u65b0:2026\u5e7410\u670814\u65e5\u6c34\u66dc\u65e5 \u5348\u5f8c10\u664230\u5206 UTC<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/div><\/div>\n","protected":false},"excerpt":{"rendered":"

EX1507783 | Exchange Online | Some users’ mailbox syncs may fail with an error in Exchange Online Status […]<\/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-18984","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"_links":{"self":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/18984","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=18984"}],"version-history":[{"count":0,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/posts\/18984\/revisions"}],"wp:attachment":[{"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/media?parent=18984"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/categories?post=18984"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/m365jp.net\/index.php\/wp-json\/wp\/v2\/tags?post=18984"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}