No errors at all anymore (at least for now)!
It may have been just a co-accident as I updated the breadcrumbs file as the new error occurred and I thought it may have been related to the PHP Catchable fatal error.
Since I removed Role Scoper and updated breadcrumbs everything works fine again.
After RS removal I noticed categories in wp-admin with 0 records, which have not been empty, because RS used them for page management purposes. Since I deleted those categories in wp-admin, posts or pages lost these pointers and breadcrumbs bug got triggered.
I hope it’s not too confusing, but when I don’t know how a plugin or app works; it’s hard to follow its behavior.