Cannot create copy of 4.61 in 4.7.2

Development Programming & Scripting
1

I cannot upgrade my 4.61 project to 4.7.2.
When I attempt this, I can see that a file structure for the project is created and populated with the 4.61 assets.
When the editor opens, it get to 94% open and hangs.
When I look in the project log, I see a whole series of the following
[2015.03.05-00.27.56:493][ 0]LogMaterial: Missing cached shader map for material BlondeWood, compiling.
[2015.03.05-00.27.56:508][ 0]LogMaterial: Missing cached shader map for material Iron, compiling.
[2015.03.05-00.27.56:523][ 0]LogMaterial: Missing cached shader map for material RopeB, compiling.
[2015.03.05-00.27.56:540][ 0]LogMaterial: Missing cached shader map for material ScrolledMetal, compiling.
[2015.03.05-00.27.58:947][ 0]LogMaterial: Missing cached shader map for material M_Landscape_Master2, compiling.
[2015.03.05-00.27.59:038][ 0]LogMaterial: Missing cached shader map for material M_Landscape_Master2, compiling.
[2015.03.05-00.27.59:200][ 0]LogMaterial: Missing cached shader map for material M_WaveFoam, compiling.
[2015.03.05-00.27.59:417][ 0]LogMaterial: Missing cached shader map for material M_Dock_Wood, compiling.
[2015.03.05-00.27.59:432][ 0]LogMaterial: Missing cached shader map for material M_Dock_Wood2, compiling.

Can anyone point out what might be going wrong and how I can fix this?

Thanks for the help in advance.

2

Is it compiling shaders? That can take some time. Enough hard drive space?