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What file types are blocked in a SharePoint Online migration?

SharePoint Online handles blocked file types differently than file types for on-premises SharePoint deployments, which may confuse users migrating to the cloud.

SharePoint Online prohibits certain file types from being uploaded to a SharePoint list or a library. The file...

types that are blocked for SharePoint Online are different from the blocked file types for local SharePoint deployments. This can cause confusion for users considering a SharePoint Online migration.

SharePoint Online blocks ASP.NET Web handler (.ashx), ASP.NET Web Services source (.asmx), JavaScript Object Notation (.json), Simple Object Access Protocol (.soap), Windows Communication Foundation service (.svc)  and Visual Studio Workflow service (.xamlx) files. These file types are permanently blocked and cannot be unblocked by SharePoint Online administrators. Blocking such files can help to bolster security and prevent unwanted changes to vital content.

Local SharePoint deployments allow administrators to add or remove file types from the list of blocked file types. SharePoint blocks more than 100 file types including Windows dynamic-link library (.dll), executable (.exe), various shortcut files -- such as .mat and .maw -- and Windows PowerShell cmdlets (.ps1 and .ps2). The method to allow or to block specific SharePoint file types will differ with the version in use.

SharePoint Online 2013 provides organizations with a cloud-based collaboration platform that can potentially free local servers and storage for other business workloads. But SharePoint Online imposes a series of limitations and rule sets that can differ from the SharePoint environment and assets currently deployed within the organization. This can present serious SharePoint Online migration problems or trigger additional costs that the company might not be prepared to handle. It's vital for administrators to review the documentation for SharePoint Online and ensure that any management schema and assets will accommodate the cloud environment before migration in order to speed the process and prevent disruption to users.

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