A soft error is a transient fault in logic or memory, often caused by environmental factors like cosmic rays, alpha particles from packaging materials, or electrical noise. The strike deposits enough charge to flip a bit from a 0 to a 1, or vice versa. Because the physical silicon remains undamaged, the error is cleared as soon as the system is reset or the corrupted data is overwritten.
Heard on the job
The server crashed due to a soft error in the cache, but a quick reboot cleared the flipped bit.
Also heard as
- single-event upset
- SEU
Do not mix it up with
- Hard error: A soft error is a temporary bit flip that clears on reset, whereas a hard error indicates permanent physical damage to the silicon.