The first error should not happen because we already have this in the Web.config file that ships with mojoPortal
<httpRuntime requestValidationMode="2.0" ...
make sure you have it in yours.
the second error I think can only be caused if you did not upload all the files or if some of them did not make it when you tried to upload.
I would re-deploy the files.
Also make sure you are using the .net 4 package of mojoPortal not the .NET 3.5 version.