java.lang.exception: input not an x.509 certificate

• upgrade your JDK (advised)
• Install the certificate manualy. To do so go on your certificate status page
• "See the certificate" button
• Download the certificate in X509 format
• install it with:
  keytool -import -trustcacerts -file cert-xxxxxxxxxx-yyyyy.cer -alias [alias-name] -keystore [keystorename]
• Then click on "See certification chain"
• Put each of the displayed pieces in a file and import them:
  keytool -import -trustcacerts -file FILE.TXT -alias [alias-name] -keystore [keystorename]
  Do not re-import the certificate if the tool indicates that it is already present.

• alias-name: name you defined when generating your CSR / private key
• keystorename: name of the file containing the keystore (a keystore is a repository of security certificates, either Certification Authority Certificates or Public Key Certificates, private key, certification chain....)