Client site suddenly getting the message above and we are able to duplicate the same issue in our development environment. Have tried a number of things to try to get past it, but no luck so far. Hasn't something changed? Is HTTP 1.1 protocol no longer available? Snippet from a trace is below. Connecting to Trello via a desktop program that has been in production and in active use for a long time now. Using Nov. 2018 openSSL DLL files. Tried using only TSL 1_2 as suggested by a 2019 post which we were already supporting but still receiving the same response.
Trace file snippet:
HTTP/1.1 426 Upgrade Required<EOL>Date: Thu, 20 Aug 2020 18:07:35 GMT<EOL>Server: globaledge-envoy
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