Forgive me for the bad English!
I have problems with compiling web build
here’s the error:
1Error
An asset is marked as dont save, but is included in the build:
UnityEditor.BuildPlayerWindow:BuildPlayerAndRun()
2Error
Building - Failed to write file: sharedassets0.assets
UnityEditor.BuildPlayerWindow:BuildPlayerAndRun()
3Error
Error building Player: Couldn’t build player because of unsupported data on target platform.
Thank you in advance for your help.
Please,help 
guys help
Same issue here. Upgraded an iOS Pro project from 3.5.7 to 4.2.2. Tried reimporting all assets; no luck. I had a few “only POT textures can be compressed to PVRTC” warnings, but I fixed those to no avail. I’m using a few Prime31 plugins, but those are working fine in another 4.2.2 iOS project.
Actually, more accurately, the process was:
-Opened 3.5.7 project set to Android platform (Pro) in 4.2.2 (without Android Pro).
-Automatically converted project.
-Switched platform to iOS Pro.
-Build fails with same 3 errors as koylan reported.
my version unity3d 4.2.2, Other projects are compiled
This is NGUI dynamic FONTS