As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIRCRAFT WAS GROUNDED: PILOT REPORTS DURING CRUISE ALTITUDE FL340 MULTIPLE FMC ISSUES- RAN FMC FAIL CHECKLIST. ON SCRATCH PAD DISPLAYED INVALID MOD PLAN WHICH PRECLUDED US FROM NAVIGATING TO ANY FIX. EMERGENCY DECLARED. MAINTENANCE REMOVED AND REPLACED FMC # 1, ALL TEST NORMAL IAW AMM 34-61-02. DOWNLOAD SOFTWARE FMC # 1 AND # 2 IAW AMM 34-61-00.