mongo:7 can't open data files written by mongo:8 (exit code 62 = NeedsDowngrade). Stay on mongo:8 — the SIGSEGV was caused by the --wiredTigerCacheSizeGB=0.25 flag, not the version. Removing the flag is the actual fix. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>