I've inherited a Sitecore upgrade from 8.0 to 8.2u7 half way through and I've found this issue which only sporadically happens.
The model item passed into the dictionary is of type 'Sitecore.Mvc.Presentation.RenderingModel', but this dictionary requires a model item of type 'Namespace.Namespace.ClientPageBase'.
This page will load fine for days and days and then (without any cause that I can detect in the logs) will throw this error. It takes down the entire site and the only way I can fix it is to stop the application pool and the start it again.
An answer to this question recommends reinstalling Glass which I have done by cleanly installing the very latest version of Glass 4 (18.104.22.1689). The issue still persists.
Another answer says that this could be a bug that is resolved in version 5.4.21 of Glass. Does anyone know if this bug could be present in version 4.5 of Glass? Is the only way to fix it to upgrade to v5? In this solution it would require a fair amount of work to do this upgrade as it uses now obsolete features.