This is due to some update regarding the way module names are managed in Slicer.

To solve the issue:

Method1: Open "Application settings", and click on "Restore default"

Method2:

1) Obtain the location of the setting file by running Slicer with command line switch "--settings-path"

For example:
jchris@karakoram:~/Projects/Slicer4-Superbuild-Debug/Slicer-build $ ./Slicer --settings-path
/home/jchris/.config/NA-MIC/Slicer.ini

2) Open the setting file with a text editor (i.e. /home/jchris/.config/NA-MIC/Slicer.ini)

3) Search for HomeModule and change "welcome" into "Welcome"

Note: Since the official version of Slicer is not yet release, no additional code has been added to automatically handle that situation.

If I understand the comment correctly, Slicer changed in that it now makes a distinction between welcome and Welcome? Whoever did that change should also change the startup in such a way that the correct search is done, when slicer is downloaded and installed?

• Slicer changed in that it now makes a distinction between welcome and Welcome?

No, before that change, module were internally referenced using their name in lowercase, now we are internally referenced using their "normal" names.

This will also help for the documentation integration, extension manager etc ...

• Whoever did that change should also change the startup in such a way that the correct search is done, when slicer is downloaded and installed?

On a fresh install of Slicer, everything will work as expected.