We were able to resolve the issue. Restored some of our root files from an older backup. Possible it’s remnants of an old hack we thought we had cleaned out.
For anyone running a search on this issue, here’s what fixed it:
If you’re on DreamHost, it’s from Memcached.
Rename object-cache back to normal. Then log in via SSH and type wp cache flush to clean the cache.
Or ask DreamHost support to flush your memcached cache.
