Portal Error: Failed to retrieve current HTTP context

Hello,

We are running v7.0.0023 Portals in production on a 2 instance Azure WebApp application.  We are occasionally running into a 'Failed to retrieve current HTTP context.' portal error that causes the entire portal to crash.  A restart of the WebApp application resolves the problem.  We are unable to reproduce the error and the problem appears to occur randomly.  We have plenty of unused room on CPU and memory server resources.  This is happening for us a couple times per week.  

Has anyone else run into this problem or know a solution?

Thanks,

Greg