--- a/toolkit/components/telemetry/Histograms.json
+++ b/toolkit/components/telemetry/Histograms.json
@@ -22,16 +22,24 @@
   },
   "A11Y_UPDATE_TIME": {
     "expires_in_version": "default",
     "kind": "exponential",
     "high": 10000,
     "n_buckets": 50,
     "description": "time spent updating accessibility (ms)"
   },
+  "ADDON_MANAGER_UPGRADE_UI_SHOWN": {
+    "expires_in_version": "53",
+    "kind": "flag",
+    "description": "Recorded when the addon manager shows the modal upgrade UI. Should only be recorded once per upgrade.",
+    "releaseChannelCollection": "opt-out",
+    "bug_numbers": [1268548],
+    "alert_emails": ["kev@mozilla.com"]
+  },
   "ADDON_SHIM_USAGE": {
     "expires_in_version": "never",
     "kind": "enumerated",
     "n_values": 15,
     "keyed": true,
     "description": "Reasons why add-on shims were used, keyed by add-on ID."
   },
   "BROWSER_SHIM_USAGE_BLOCKED": {

--- a/toolkit/mozapps/extensions/internal/XPIProvider.jsm
+++ b/toolkit/mozapps/extensions/internal/XPIProvider.jsm
@@ -2928,16 +2928,18 @@ this.XPIProvider = {
    * Shows the "Compatibility Updates" UI.
    *
    * @param  aAddonIDs
    *         Array opf addon IDs that were disabled by the application update, and
    *         should therefore be checked for updates.
    */
   showUpgradeUI: function(aAddonIDs) {
     logger.debug("XPI_showUpgradeUI: " + aAddonIDs.toSource());
+    Services.telemetry.getHistogramById("ADDON_MANAGER_UPGRADE_UI_SHOWN").add(1);
+
     // Flip a flag to indicate that we interrupted startup with an interactive prompt
     Services.startup.interrupted = true;
 
     var variant = Cc["@mozilla.org/variant;1"].
                   createInstance(Ci.nsIWritableVariant);
     variant.setFromVariant(aAddonIDs);
 
     // This *must* be modal as it has to block startup.