During importing 'AQUAS Water/River Set' A$ package, among other warning/error messages, there are:
Binary to YAML conversion: type unsigned int is unsupported

These go in Editor.log as:
---
Binary to YAML conversion: type unsigned int is unsupported

(Filename: /Users/builduser/buildslave/unity/build/Runtime/Mono/BackupState.cpp Line: 89)
---

These don't bring any value to the user and should either be not there or provide more information, so the user may take an action.

The issue comes up every now and again since 5.0. It is mentioned a number of times on the forum, like https://forum.unity3d.com/threads/binary-to-yaml-conversion-type-unsigned-int-is-unsupported-etc.293330/. Also, cases 728741, 788003 and some other mention the error.

To reproduce:
Encountered on OS X 10.12.5 with Unity 2017.2.0b2 (a9976befbe0f).
- New project
- Import 'AQUAS Water/River Set' A$ package
- Agree to API update
>>> After the update will stop, there will be 4 such error messages.
Expected: These should either be not there, or provide some information to the user, whereupon he can take an action.

Is not reproducible with 5.6.2 and 2017.1.0f3, for the same A$ package. But doesn't look to be a regression, since it was complained upon earlier.