Hi Simon,
If old data sources are exist at delivered version at ecc Tx - RSA5, they may work. or
as my guess new data sources have same functionality of old data sources along with new features.
But above error indicates you may need some note for that. if possible with the same error description you can check at sap market place you may get relevant oss note.
Have a look at SAP Notes 1165059 & 1251433.
Mean while check Mr Vivek Das Gupta reply from below thread may be useful.
http://scn.sap.com/thread/1222949
Thanks