I'm pretty sure the last time I updated Node Red, the custom nodes I had previously installed had disappeared and I had to manually install them again. I once again would like to update Node Red to the latest version and was wondering if there is a way to do this whilst keeping the custom nodes intact.
I seem to remember a similar situation where i had to do this.
Now, for un-published nodes and test situations, I drop a copy of the node-red-my-custom-node (full folder) into .node-red/nodes/ - this survives the update process
Then they should all still be there - with the exception that some nodes were removed from core some time back (cant remember exactly - something like email node was taken out of core in the update between v0.20.x ~ v1.0.0)
If you are concerned, take a backup before you start & a screen shot of installed nodes (then re-install if need be)