Hello!
Thank you so much for octoPi, it greatly facilitates the work, but there is one problem that I would like to solve. There is a raspberry pi 3 b +, octoprint 1.3.8 installed with octopi-stretch-lite-0.15.1.
The system works, I print from it, but I cannot install plugins. It gives an error.
The possibility of updating is also blocked.
I unfortunately understand badly in Unix systems, I hope for your help
You might try remoting into your Raspberry Pi with something like ssh pi@octopi.local and using raspberry as the default password.
Next, check the first line of the file seen here sudo nano /usr/bin/lsb_release. If the first line doesn't seem to have a 2.x version of Python, then this would show itself with the error you have. The first line should be more like #!/usr/bin/python2.7 instead. If you used the standard OctoPi image then you shouldn't be seeing this error.