There was a JPL probe years ago (can't remember which, and can't seem to find a reference) that had a radiation hardened memory IC with error correcting codes and a system to detect and correct the bit flips that were expected due to cosmic rays.
After launch, the number of unrecoverable errors (due to multiple bits flipped within the same codeword) was higher than expected. It turned out that someone had swapped some combination of address or data lines, which ended up changing the physical grouping of bits within the codewords. Some of the bits within a logical codeword were so close together that a single event was able flip both of them, causing the error correction to fail.
After launch, the number of unrecoverable errors (due to multiple bits flipped within the same codeword) was higher than expected. It turned out that someone had swapped some combination of address or data lines, which ended up changing the physical grouping of bits within the codewords. Some of the bits within a logical codeword were so close together that a single event was able flip both of them, causing the error correction to fail.