If the pages no longer render because they use a control that isn't in the SafeControls list, follow these steps:
- Review SharePoint Unified Logging Service (ULS) logs to find the 9s9ay tag or a message that contains "Blocking control with property" that indicates that a control is blocked.
- Identify the type, namespace, and assembly strong name from the error message.
Given the following error message:
"The type Contoso.Customizations.WebPartControl, Contoso.WebParts, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b03f5f8f11d50a3a could not be found or it is not registered as safe."
Type = "WebPartControl"
Namespace = "Contoso.Customizations"
Assembly strong name = "Contoso.WebParts, Version=1.0.0.0, Culture=neutral, PublicKeyToken=b03f5f8f11d50a3a"
Given the following error message:
"Blocking control with property traversal markup. [tagName: SharePoint:WebPartControl][propName: propName1][type: typeName1]"
Type = "WebPartControl" (not "typeName1")
You can find the namespaces and assembly data in Microsoft Docs by querying the type name.
- Add a new SafeControls element for the given type, namespace, and assembly strong name to the Web.config file under the configuration/SharePoint/SafeControls element, as described in SafeControls element (Solution), and then set the Safe attribute to TRUE.
For more information about the format of the attribute values in the SafeControls element, refer to the table in the step 12 in Marking Safe Controls in the Package Designer.