The question to ask is: Will you be using any “modern” (2.x) Binding?
If the answer is: Yes (most likely): Then, you will need to configure Things (either using PaperUI and/or using *.things flat text files)
If you stay with only legacy (1.x) Bindings, then you will not use the new 2.x concepts (Things, Channels, etc)
In your example, you are already using the systeminfo addon, which is a 2.x Binding, so you will need Things.
Note: There is also the legacy version (1.x) of : https://www.openhab.org/addons/bindings/systeminfo1/ but you should use the newer (2.x) one
Did you create Things for this binding using PaperUI? Check the Channel UID from PaperUI to make sure it is correct. If you have no Things defined for the systeminfo addon: then the Items will not be linked to any Channel (of a Thing) and will get no updates.
I have to check this one… I don’t remember its root-cause atm.
edit: check: AbstractRegistry raises Exception about ADDED event!: null - #2 by Kai
@rlkoshak invested alot of time to type up this: Migration from openHAB 2 | openHAB. Check it out.