What Are the Common Causes for a Miner to Generate an “Invalid Share”?

Common causes for an invalid share include hardware errors (e.g. faulty ASIC chips or memory), software bugs in the mining client, or overclocking the hardware too aggressively, which leads to computational errors. They can also be caused by a malicious miner attempting to submit a fabricated proof-of-work.

The pool's Stratum server is designed to quickly detect and reject these shares.