Sorry for continuing an old thread, but I have a similar problem in that I need to use Teensy 4.0/1 with Arduino but a much better front end. Having read this thread and others and I am trying to install the Sloeber package. Here is what I am doing. I am leaving the Teensyduinoinstall until I have the basics of Sloeber working :
1. Download arduino-1.8.13-windows.zip and extract it into a new folder in the root of G:\
2. Create a directory called portable under the arduino directory and run arduino once to initialise the portable structure.
3. Download V4.3.3_win64.2020-04-23_11-36-51.zip and extract to a new directory in the root of G:\
4. Run sloeber-ide.exe in the Sloeber directory (tried as Admin too)
It gets a little way into the installation and then during the "Finishing the Installation" dialog, it fails with a dialog :
Problem Occured
Failed to configer sloeber
See Details for more info.
Pressing Details button opens a text pane under the dialog with the text :
Failed to configer Sloeber
Failed to install [DEPRECATED] Arduino mbed-enabled Boards
Failed to download "http://downloads.arduino.cc/cores/ArduinoCore-mbed-nonexistant.tar.bz2".
Failed to download url
http://downloads.arduino.cc/cores/ArduinoCore-mbed-nonexistant.tar.bz2 error code is: 404
This problem rears its head many times in lots of duplicate error posts with no positive conclusion. Drilling to the root report, there is a reply by (I believe) one of the authors saying something like "I don't see what the problem is, this is a one off installation thing. Just make sure your project does not use the deprecated arduino board.". The problem of course is that if you can't install it you can't get as far as starting a project with any arduino board at all. I wanted to try the "Nightly" build to see if it helps, but I can only find it as an Eclipse plugin which is not a good place for me to go at the moment.
I am totally stumped on this. I would be very happy to hear of any ideas or solutions please. Thanks.
Optician