No issue here. Please start Firefox in Safe Mode by holding down Shift when clicking the startup link, or by choosing Help > Restart with add-ons disabled and see if the issue is still there. If not, restart Firefox in normal mode and disable the IBM Security Rapport add-on only, followed by the Default Bookmark Folder add-on in case it does not help.

Also note you seem to have a file called user.js in your profile folder that may contain some code causing the issue. The file could have been added by external software. Try removing it (or make sure the software doesn’t add it) when Firefox is not running.

Your onto something! Firefox safe mode allowed ebay.fr to open a tab, so I disabled IBM Security Rapport to see if that worked. I also deleted the user.js file. Problem still there, so I re-enabled Rapport, and disabled uBlock Origin, and hey presto, ebay.fr works as it should. Does this mean that the add-on is at fault, or just that it is not compatible with Firefox 59.0.2 ?

Good... Out of the 3 add-ons you use, I thought uBlock Origin should not be the one causing the issue, hence I didn’t mention it. ;)

uBlock Origin does not cause the issue for me in a 59.0 Nightly build (I don’t have 59.0.2. installed right now), but I don’t think this is an incompatibility issue but rather some filter or other setting. Did you change or add anything in its filters?

Can you check its Logger (Journal des requêtes réseau) to see what is blocked? All that is blocked here when opening a main page link in a tab are images from rover.ebay, but that should probably not cause the opened tab to close right after. Either way, make sure the add-on is up to date (it just got updated) and try using default settings and filters. You could also try uninstalling and reinstalling it first.