OCSP responder sent invalid "Content-Type" header: "text/html" while requesting certificate status,

[cpu]

I believe this is the same problem as Seem that OSCP servers down again

There is a partial outage for OCSP service presently: https://letsencrypt.status.io/pages/incident/55957a99e800baa4470002da/5978f3a9045a58b3050002d3