Some time between Tuesday (10-15) and today (10-17) all of the computers in my lab using Linux, including my Raspberry Pi computers, stopped being able to access the HTML/CSS editing interface. They can load other sections/levels but the bottom half of the screen where they do the actual work gives an error message.
This has brought be down to 9 working computers for a class of 27. Was a change made recently on Code.org’s back end?
Hi Aaron,
Here is a support article that helps with troubleshooting: https://support.code.org/hc/en-us/articles/360016804871-Troubleshooting-Web-Lab-problems
I wonder if your IT department restricted access to the domains. This is probably the best place to start.
Karen
Hello, Karen
Thank you for your help. It turns out that the HTML editor breaks when viewed in a private browsing window in Firefox. (Long story short: Younger students kept forgetting to log out so having Firefox forget everything made their accounts more secure.)
Not sure about the how or why for why private browsing breaks ANYTHING other than some tracking methods, but things are back to normal.
Glad you got it working, @aaron.smith! and THANK YOU for commenting what the solution was, so that someone reading this forum a few months (or even years) down the line will know how to fix the problem! 
–Michael K.
