Hello Akshat,
Listed below are few issues which I have encountered
1> The count mismatch example in the legacy if you have 25 k customer after cutover in the SAP - you found only 24K customers - some problem in loading
2> Fields mismatching from the legacy to the SAP ( this happens due to the wrong logic written to convert the data from legacy to SAP)
3> Some characteristics issues - For example if a SAP field data elements has 15 characters but if the data we load is greater than that it causes problems
4> Few issues due to the lack of configuration - for example if the plant field is mandatory in the account group and if that field is not mandatory in legacy - it causes problem when you edit that customer post cutover.
Thank you for your time.
Regards,
Siva.