diff --git a/internal/service/service.go b/internal/service/service.go
index 851320e..3c3c4d5 100644
--- a/internal/service/service.go
+++ b/internal/service/service.go
@@ -211,7 +211,6 @@ func (svc *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			slog.String("path", r.URL.Path),
 		))
 	)
-
 	// Log completion time.
 	defer func() {
 		log.InfoContext(
@@ -249,6 +248,9 @@ func (svc *Service) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 
 	log.InfoContext(ctx, "handling")
 
+	// Always set request ID header.
+	w.Header().Set("X-Request-ID", id)
+
 	// Pass the request on to the multiplexer.
 	svc.mux.ServeHTTP(w, r)
 }
diff --git a/internal/service/static/main.js b/internal/service/static/main.js
index 40053d4..7325f25 100644
--- a/internal/service/static/main.js
+++ b/internal/service/static/main.js
@@ -657,14 +657,21 @@ class Odidere {
           body: JSON.stringify(payload),
           signal: this.currentController.signal,
         });
+        const requestId = res.headers.get('X-Request-ID') || '';
+
         if (!res.ok) {
           const err = await res.text();
-          throw new Error(`server error ${res.status}: ${err}`);
+          this.renderer.renderError(
+            `server error ${res.status}: ${err}`,
+            requestId,
+          );
+          return;
         }
 
         for await (const { eventType, event } of this._parseSSEStream(res)) {
           if (event.error) {
-            throw new Error(event.error);
+            this.renderer.renderError(event.error, requestId);
+            return;
           }
 
           if (
diff --git a/internal/service/static/render.js b/internal/service/static/render.js
index 955d91b..ebfc6e4 100644
--- a/internal/service/static/render.js
+++ b/internal/service/static/render.js
@@ -403,11 +403,17 @@ export class Renderer {
    * renderError renders an error message in the chat.
    * @param {string} message
    */
-  renderError(message) {
+  renderError(message, requestId = '') {
     const $msg =
       this.$tplErrorMessage.content.cloneNode(true).firstElementChild;
-    $msg.querySelector('.message__content').textContent = message;
-    $msg.dataset.copyText = message;
+    const $content = $msg.querySelector('.message__content');
+    if (requestId) {
+      $content.textContent = `Request: ${requestId}\n${message}`;
+      $msg.dataset.copyText = `Request: ${requestId}\n${message}`;
+    } else {
+      $content.textContent = message;
+      $msg.dataset.copyText = message;
+    }
     this.$chat.insertBefore($msg, this.$chatLoading);
     this.scrollToBottom();
   }