Voyager 1: "a single chip responsible for storing part of the affected portion of the FDS memory isn't working ... the chip could have been hit by an energetic particle from space or that it simply may have worn out after 46 years"

https://www.livescience.com/space/space-exploration/nasa-engineers-discover-why-voyager-1-is-sending-a-stream-of-gibberish-from-outside-our-solar-system