Some panels are taking too much time to load. Could you check if you still have deprecated ones - see Remove deprecated "Panels.SpaceDocs", "Panels.Spaces", "Main.Spaces" and "Main.SpaceIndex" - thought I had a better link but can’t find it right now. The blog panel could also be the root cause with a lot of blog entries…or a custom panel that is long to load. Finally, try to increase Nginx timeout limit, if possible…
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