This page lists any changes in 2017.1 which might affect existing projects when you upgrade from earlier versions of Unity.
Changes in data format which may require re-baking.
Changes to the meaning or behavior of any existing functions, parameters or component values.
Deprecation of any function or feature. (Alternatives are suggested.)
UnityWebRequestTexture.GetTexture() nonReadable parameter change
This convenience API had a bug where nonReadable worked the opposite way then it should, that is setting it to true would result in a readable texture and vice versa. Now this has been corrected and parameter works the way it’s documented. Note, that if you create DownloadHandlerTexture directly, you are not affected.
Particle System Stretched Billboard Pivot parameter change
X axis pivots are now accurate on Stretched Billboards. You may need to reconfigure your pivot settings on affected projects.
Y axis pivots are also accurate now and Unity automatically reconfigures these pivots when you upgrade your project.