Sorry, about that. I took what the form generated and forgot to edit it to open in the classic notebook interface. I edited it now and tested it. You can also try the launch from here. (Remember, this isn’t the one to use because appmode doesn’t get enabled in that one. It was more of an intermediate I tried to see if I could go that route if environment.yml use seemed troublesome. Use my current fork as a guide because appmode is running there.)
I’m confused by this. If you launch from my fork via 
, and press the appmode button on the toolbar when the notebook comes up (or simply use the URL I show next below), you’ll see the appmode view works fine again. And so I’m confused why you are saying that and asking what to do next? By the way, you can launch directly into Appmode and not tell people to press the button at top of you notebook. For mine the following URL will open directly in the appmode view:
http://mybinder.org/v2/gh/fomightez/EPA/HEAD?urlpath=%2Fapps%2Fappmode_all.ipynb
You can use that pattern to design your own launch URL after to add a binder directory to your repo and place a copy of the environment.yml I made in it. (I’d suggest also deleting nbinteract,too, see the ‘aside’ below; however, that deletionis optional.)
You don’t need to roll anything back here because your older version isn’t going to work with the updated MyBinder environment as well as what I’ve guided you to do now. More importantly, you don’t need to roll back to test because you can have MyBinder launch with previous commits by using the form at MyBinder.org to build the launch link. There a spot on the form for putting in commits using the commit ID tag from the history. That is how I provided one to test where I just used requirements.txt.
An aside:
Also, the default ability to launch to JupyterLab and not see the 404 error should be restored if you remove nbinteract from your environment.yml in your binder directory. For some reason, that seems to interfere with the MyBinder system default installation of JupyterLab. Because JupyterLab is then not installed, it fails with the 404 screen with the launch link you like you posted in your reply here. Your launch link just the standard one and so it tries to default to JupyterLab.