Cannot register Confluence due to 'License you entered was not valid' error - Confluence User Guides and Documents

If this happens, please check your logs. The following message may appear:

2006-03-19 16:32:05,969 ERROR [atlassian.license.decoder.LicenseDecoder] String) Exception looking up public key: null
java.security.spec.InvalidKeySpecException
   at gnu.java.security.provider.DSAKeyFactory.engineGeneratePublic(java.security.spec.KeySpec) (/usr/lib/libgcj.so.6.0.0)
   at java.security.KeyFactory.generatePublic(java.security.spec.KeySpec) (/usr/lib/libgcj.so.6.0.0)
   at com.atlassian.license.decoder.LicenseDecoder.getPublicKey(java.lang.String) (Unknown Source)
   at com.atlassian.license.decoder.LicenseDecoder.getLicense(com.atlassian.license.LicensePair, java.lang.String) (Unknown Source)
   at com.atlassian.license.LicenseManager.setLicense(java.lang.String, java.lang.String) (Unknown Source)
   at com.atlassian.confluence.setup.actions.SetupLicenseAction.validateLicense() (Unknown Source)
   at com.atlassian.confluence.setup.actions.SetupLicenseAction.validate() (Unknown Source)

If you see this, you are most likely using GCJ/Kaffe, which sometimes has problems running Confluence. Please try using the Sun JDK.