This message appears when savecore(1M), if activated, tries to copy a debugging image of kernel memory to disk, but cannot read various kernel data structures correctly. Generally, this occurs after a system panic has corrupted the main memory. Data corruption on the system is possible.
Look at the kernel error messages that preceded this one to try to determine the cause of the problem. Error messages such as BAD TRAP usually indicate faulty hardware. Until the problem that caused the kernel panic is resolved, a kernel core image cannot be saved for debugging.