Odd redirect loop when flushing or building via the browser

<%- if @topic_view.topic.tags.present? %>
<%= t 'js.tagging.tags' %>: <%- @topic_view.topic.tags.each do |t| %> <%= t %> <%- end %>
<% end %>

I have moved a number of sites from one server to another. Having done this they are now go into a weird redirect loop whenever I try to run a flush or dev/builld

I get a series of SS warnings at the top of the page followed by:

Redirecting to http://domainname.co/Security/login?BackURL=%3Fflush%3D1%26urlspecialstoken%3D902137be

This loops every few seconds with the token changing each time. It then throws a 429 error.

I haven’t seen this behaviour before. What would be causing it?

The new server is a standard Debian 9 build. Nothing odd about it

Thanks
Richard

It’d be worth knowing what the series of warnings are… there might be some clues in there.

The warnings are just ones about templates and the like. They aren’t part of this issue.

Does it try to redirect from /Security/login to /Security/login?
Would you be able to check it with curl, wget or httpie without actually following the redirect?