The certification authority (CA) failed to encode a server extension required to validate a certificate or certification ...

The certification authority (CA) failed to encode a server extension required to validate a certificate or certification revocation list (CRL). The CA will not issue any certificates or CRLs that do not contain this extension. To correct this problem, use the Certification Authority snap-in to remove any Unicode characters in the URLs for the AIA, CDP, and IDP extensions, then restart the CA.