import bookmarks error - can't access property "toolbar_____". t is undefined

I'm using Memex Firefox Browser Extension Version 3.19.30 installed via the Firefox Add-ons: https://addons.mozilla.org/pt-BR/firefox/addon/worldbrain/

I started importing my bookmarks, 31 were successful, there were some failures, then all the following batches started failing with error 404 or 503 (normal, because those links are down), but then I noticed all others working websites with this error:

can't access property "toolbar_____". t is undefined