https://support.ledgerwallet.com/hc/en-us/articles/115005161925-How-to-use-Electrum-with-your-Nano-S
I was in the process of configuring the Electrum by running the Electrum Installation wizard according to the tutorial above.
After the Ledger Nano was detected I got :
"NoneType object has no attribute 'handler' "
I retried by restarting Electrum, reconnecting the ledger etc. to no avail.
Any ideas?