There are a number of uncertainties and disputed issues in the early history of Islam.
Most of these disputes can be traced to Shi'a-Sunni disagreements. Shi'a often argue that history has been distorted to further a Banu Umayyad agenda. In many cases, complications with the historiography of early Islam have also resulted in lack of consensus within denominations of Islam.
List of disputed issues
The uncertainties include:
References
Disputed issues in early Islamic history Wikipedia(Text) CC BY-SA