diff --git a/client/js/options.js b/client/js/options.js
index b4eaaaa1..f741fbd3 100644
--- a/client/js/options.js
+++ b/client/js/options.js
@@ -281,7 +281,7 @@ function initialize() {
 	}
 
 	$settings.on("change", "input, select, textarea", function(e) {
-		// We only want to trigger on human triggerd changes.
+		// We only want to trigger on human triggered changes.
 		if (e.originalEvent) {
 			const $self = $(this);
 			const type = $self.prop("type");
diff --git a/client/js/socket-events/configuration.js b/client/js/socket-events/configuration.js
index 2a6fec17..1a7bf32c 100644
--- a/client/js/socket-events/configuration.js
+++ b/client/js/socket-events/configuration.js
@@ -25,6 +25,12 @@ socket.on("configuration", function(data) {
 	options.initialize();
 	webpush.initialize();
 
+	// If localStorage contains a theme that does not exist on this server, switch
+	// back to its default theme.
+	if (!data.themes.map((t) => t.name).includes(options.settings.theme)) {
+		options.processSetting("theme", data.defaultTheme, true);
+	}
+
 	const forms = $("#connect form, #change-password form");
 
 	forms.on("submit", function() {
diff --git a/src/server.js b/src/server.js
index af04d8c4..0971fb9c 100644
--- a/src/server.js
+++ b/src/server.js
@@ -555,6 +555,7 @@ function getClientConfiguration() {
 	config.version = pkg.version;
 	config.gitCommit = Helper.getGitCommit();
 	config.themes = themes.getAll();
+	config.defaultTheme = Helper.config.theme;
 
 	if (config.displayNetwork) {
 		config.defaults = _.clone(Helper.config.defaults);