diff --git a/Upgrading-1.0-to-1.1.md b/Upgrading-1.0-to-1.1.md
index 69de714..c683142 100644
--- a/Upgrading-1.0-to-1.1.md
+++ b/Upgrading-1.0-to-1.1.md
@@ -13,4 +13,8 @@ If you are running the server with a persistent database store, you will need to
 1. Shut down the version 1.0 server
 1. Connect to the MySQL or HSQL database as a user with appropriate rights
 1. Run the appropriate upgrade script
-1. Deploy the version 1.1 server
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+1. Deploy the version 1.1 server
+
+## Existing data
+
+Existing authorizations are incompatible between 1.0 and 1.1. All active access tokens must be revoked (or translated using some form of external process) during the upgrade process. Note that this includes any Registration Access Tokens used for dynamically registered clients. Otherwise, all authorization grants, clients, whitelists, blacklists, and scopes may remain in place following the instructions above. 
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