I am afraid you are not telling us much to work with as it is. We have several different LMS platforms and it makes a difference which one you are currently using.
What is the URL you use to log in?
Please have a look around the menu area at the top of the page in your online learning environment - there should be a link you can use to request help from the RHT support team, which will create a support ticket and have someone respond to you really quickly.
I hope you manage to fix your problem really soon and continue with your learning!
I notice this with my own Standard Learning Subscription. Though the error doesn't seem to stop the interface from providing the class content that I've requested. Generally I just click OK and things behave as expected.