Event ID - 647

Event Id647
SourceMicrosoft-Windows-ADFS
DescriptionThe Federation Service encountered an error while loading the trust policy. Multiple Active Directory Domain Services account stores are configured. If this error occurs during startup of the Federation Service, the Federation Service will be not be able to start, and all requests to the Federation Service will fail until the configuration is corrected. If this error occurs while the Federation Service is running, the Federation Service will continue to use the last trust policy that was loaded successfully. User Action This should occur only if the trust policy file has been modified without use of the AD FS administrative tools. Reduce the number of Active Directory Domain Services account stores in the trust policy to one.
Event Information According to Microsoft :

Cause :

This event is logged when the Federation Service encountered an error while loading the trust policy.

Resolution :

Reduce the number of Active Directory account stores to one

This error occurs only if the trust policy (trustpolicy.xml) file has been modified without the use of the Active Directory Federation Services snap-in and the modification causes another relying parameter to fall outside the scope of acceptable values. In this case, the manual change that was made to the trustpolicy.xml file increased the number of allowable Active Directory account stores above the maximum value per Federation Service, which is 1.

To correct the problem, edit the trustpolicy.xml file using NotePad, and confirm that only one instance of Active Directory Domain Services (AD DS) appears in the AccountStore XML element tags.

Verify :

Verify that you can access the Active Directory Federation Services (AD FS)-enabled application from a client browser and that the resource can be accessed.
Reference LinksEvent ID 647 from Source Microsoft-Windows-ADFS

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