diff --git a/www/checkup/dependency-warning.js b/www/checkup/dependency-warning.js
new file mode 100644
index 000000000..0b11fcf1e
--- /dev/null
+++ b/www/checkup/dependency-warning.js
@@ -0,0 +1,17 @@
+(function () {
+ var first = true;
+ window.addEventListener('error', function (ev) {
+ if (!ev) { return; }
+ var srcElement = ev.srcElement;
+ if (!srcElement) { return; }
+ var nodeName = srcElement.nodeName;
+ if (nodeName !== 'SCRIPT') { return; }
+ var src = srcElement.src;
+ if (!/\/bower_components\/.*/.test(src)) { return; }
+ if (first) {
+ document.write(`It's possible that this server's administrators forgot to install its client-side dependencies with 'bower update'.
`);
+ first = false;
+ }
+ document.write(`Failed to load ${src}.
`);
+ }, true);
+}());
diff --git a/www/checkup/index.html b/www/checkup/index.html
index 04a9502d3..9015d10f2 100644
--- a/www/checkup/index.html
+++ b/www/checkup/index.html
@@ -3,6 +3,7 @@
+