Symptoms
Online store fails with the error "ERR_TOO_MANY_REDIRECTS" (http error 303) when a customer purchases a plan with APS2 resources and the option SHOW_APPLICATION_SERVICE_PARAMETERS is switched on for the screen in a purchase scenario (e.g. Azure CSP service plan).
Cause
.htaccess was not updated with the new redirect rules.
Resolution
If store is configured through brand:
System > Settings > Brands > brand name, click "Edit", and click "Submit"
If store is installed as a proxy the easiest way would be reinstalling proxy store. Otherwise it is required to edit the .htaccess manually:
RewriteRule ^%URL_SUFFIX%(index\.php[^\?]*) @@host@/$1/?StoreID=@@StoreID@&subdir=%URL_SUFFIX%&%{QUERY_STRING} [P,L]
instead of previous
RewriteRule ^%URL_SUFFIX%index\.php.* @@host@/index.php?StoreID=@@StoreID@&subdir=%URL_SUFFIX%&%{QUERY_STRING} [P,L]