LimeSurvey version: 7.9.1
Own server or LimeSurvey Cloud: Own server
Survey theme/template: -
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after the update from 6.5 to 7.9.1 no admin can open any survey (existing or new) as the browser falls into an endless loop of redirects
url changes e.g. between 
https://--ourdomain--/surveyAdministration/view/?surveyid=43354 resulting in 302 redirecting to:
https://--ourdomain--/index.php/editorLink/index?route=survey%2F43354 resulting in 302 redirecting to:
which loads 
https://--ourdomains--/editor/#/survey/43354
with some CSS and JS.
then some command in https://--ourdomain--/editor/build/static/js/index.ebd6522c.js starts the loop from the beginning (from firefox network analyze)