weakest link

Etymology
The figurative sense comes by metaphor from the literal sense: the notion that a chain is only as strong as its weakest link. (See historical details there.)

Noun

 * 1) The part of a system that is most likely to fail or cause problems.

Translations

 * Dutch: zwakste schakel
 * Finnish: heikoin lenkki
 * French:
 * German: schwächstes Glied
 * Hungarian: leggyengébb láncszem
 * Italian: anello debole
 * Polish: najsłabsze ogniwo
 * Russian: сла́бое звено́
 * Spanish: eslabón más débil
 * Swedish: svagaste länken ,