Hi Christian,
This error occurs when attempting to decrypt an encrypted string using the wrong encryption key. The encryption keys are stored in the <appSettings>
section of server configuration file:
<add key="Continua.HashSalt" value="***"/>
<add key="Continua.SymmetricEncryptionKey" value="***"/>
<add key="Continua.SymmetricEncryptionVector" value="***"/>
When migrating ensure that these keys are copied from the old server to the new server.
The sever configuration file is located at <continua_install_path>\Server\Continua.Server.Service.config. By default, this is at %ProgramFiles%\VSoft Technologies\ContinuaCI\Server
Note that this file also contains the connection string for the database.