16913: Add upgrade note about LoginCluster

Arvados-DCO-1.1-Signed-off-by: Peter Amstutz <peter.amstutz@curii.com>

diff --git a/doc/admin/upgrading.html.textile.liquid b/doc/admin/upgrading.html.textile.liquid
index 1eb2468c321c058298acc7316b23ca23d243f2f8..de700d5598083e28fe2a8c5a333c1bb2b143f7bb 100644 (file)
--- a/doc/admin/upgrading.html.textile.liquid
+++ b/doc/admin/upgrading.html.textile.liquid
@@ -35,10 +35,14 @@ TODO: extract this information based on git commit messages and generate changel
 <div class="releasenotes">
 </notextile>
 
-h2(#master). development master (as of 2020-09-22)
+h2(#master). development master (as of 2020-09-28)
 
 "Upgrading from 2.0.0":#v2_0_0
 
+h3. LoginCluster conflicts with other Login providers
+
+A satellite cluster that delegates its user login to a central user database must only have `Login.LoginCluster` set, or it will return an error.  This is a change in behavior, previously it would return an error if another login provider was _not_ configured, even though the provider would never be used.
+
 h3. Minimum supported Ruby version is now 2.5
 
 The minimum supported Ruby version is now 2.5.  If you are running Arvados on Debian 9 or Ubuntu 16.04, you may need to switch to using RVM or upgrade your OS.  See "Install Ruby and Bundler":../install/ruby.html for more information.