„Die Mandantenseiten sind derzeit schreibgeschützt“ – HTTP 507, obwohl nur 290 GB des 1.167 GB großen Mandantenkontingents genutzt werden.

A Microsoft 365 tenant (commercial & IUR as partner) has been read-only across all SharePoint Online sites and all OneDrive accounts since 17 September 2026. No user can upload, edit or save anything. This has now lasted 11 days.

Symptoms

• SharePoint: "Tenant sites are in read-only right now"
• OneDrive: "Your organization's storage is full. Your OneDrive is read-only right now."

Evidence from a HAR trace of a failing upload

23 Sep 2026, 10:59:59 GMT

POST /_api/web/GetFolderByServerRelativePath(...)/Files/AddUsingPath(...)

HTTP 507 Insufficient Storage

{"error":{"code":"-2147023080, Microsoft.SharePoint.SPException",

 "message":"Tenant sites are in read-only right now"}}

SPRequestGuid / request-id: 

MicrosoftSharePointTeamServices: 16.0.0.27702

-2147023080 = 0x80070718 = ERROR_NOT_ENOUGH_QUOTA. So the service rejects the write as a quota condition.

What does not match

• Get-SPOTenant: StorageQuota = 1,195,008 MB (approx. 1,167 GB), StorageQuotaAllocated = 0
• Sum of StorageUsageCurrent over all sites including personal sites: approx. 290 GB
• Reports > Storage in the admin center is not available for this tenant ("You must be signed into an account with required roles to view this page. Make sure you're also signed into a Microsoft 365 Education or Trial tenant"), so Education pooled storage should not apply
• Service health shows no incident
• No Quota-Messages per Mail or in Admin-Centers

What was tried, without any effect

• Connected Microsoft 365 SharePoint Storage and Microsoft 365 OneDrive Storage (pay-as-you-go) on 18 Sep
• Purchased Office 365 Extra File Storage (700 GB) on 18 Sep. StorageQuota is unchanged, and the subscription shows status "Suspended" in the directory

Support status

Two cases, 11 days, no resolution. The first (<[Moderator note: Personally Identifiable Information removed]>) was closed as "redirected to right support path". The second (<[Moderator note: Personally Identifiable Information removed]>) is still Severity C and still running with no result

Questions

1. Which backend condition can put an entire tenant into read-only with ERROR_NOT_ENOUGH_QUOTA while the reported tenant quota is only about 25 % consumed?
2. What is the correct escalation path to get the SPRequestGuid above examined in the backend?

Any pointer appreciated.