From 16452cd007ae12ff41128da2d9bd6199f5630eaa Mon Sep 17 00:00:00 2001
From: Andre Wanlin <67169551+awanlin@users.noreply.github.com>
Date: Fri, 4 Aug 2023 16:03:51 -0500
Subject: [PATCH] added empty return

Signed-off-by: Andre Wanlin <67169551+awanlin@users.noreply.github.com>
---
 .changeset/fluffy-pens-prove.md                    | 5 +++++
 plugins/auth-backend/src/lib/oauth/OAuthAdapter.ts | 1 +
 2 files changed, 6 insertions(+)
 create mode 100644 .changeset/fluffy-pens-prove.md

diff --git a/.changeset/fluffy-pens-prove.md b/.changeset/fluffy-pens-prove.md
new file mode 100644
index 0000000000..0bd7d9baf3
--- /dev/null
+++ b/.changeset/fluffy-pens-prove.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-auth-backend': patch
+---
+
+Updated `frameHandler` to return `undefined` when using the redirect flow instead of returning `postMessageReponse` which was causing errors
diff --git a/plugins/auth-backend/src/lib/oauth/OAuthAdapter.ts b/plugins/auth-backend/src/lib/oauth/OAuthAdapter.ts
index 5f51b2d301..fb0750f0cb 100644
--- a/plugins/auth-backend/src/lib/oauth/OAuthAdapter.ts
+++ b/plugins/auth-backend/src/lib/oauth/OAuthAdapter.ts
@@ -187,6 +187,7 @@ export class OAuthAdapter implements AuthProviderRouteHandlers {
           );
         }
         res.redirect(state.redirectUrl);
+        return undefined;
       }
       // post message back to popup if successful
       return postMessageResponse(res, appOrigin, responseObj);