From Longman Dictionary of Contemporary Englishcome up against something/somebody phrasal verbPROBLEMto have to deal with problems or difficulties We may find we come up against quite a lot of opposition from local people. You’ve got no idea of what you’re going to come up against. → come→ See Verb table
Examples from the Corpus
come up against • In every direction he came up against his own incompleteness.• They looked at each other with the knowledge that they had come up against the edge of the permissible.• He repeated his question, and came up against the same smiling ignorance.• When Blue comes up against this question, he can no longer think. 