Q: What to do if there is an error when iServer starting and failed to connect the oracle datasource?

A: 1. iServer should have the same bit with oracle client. Please check the bit. 
    2. Whether you can connect to oracle service through SQLPLUS. 
    3. iServer version should higher than the version of making data. 
    4. Try using the same version and number of iDsektop to see whether you can open it.