This document presents a systematic review of uncertainties in software project management. It identifies key sources of uncertainty through a review of 2,933 publications, selecting 23 for full analysis. The review aims to understand the relationship between uncertainty and innovative projects, identify common sources of uncertainty, and determine practices for reducing uncertainty in project management. A multi-step process was used, including defining research questions, searching multiple databases, selecting publications, assessing study quality, and extracting relevant data.