diff --git a/.changeset/dull-rings-arrive.md b/.changeset/dull-rings-arrive.md
new file mode 100644
index 0000000000..3e1827dc9c
--- /dev/null
+++ b/.changeset/dull-rings-arrive.md
@@ -0,0 +1,5 @@
+---
+"@blitzjs/auth": patch
+---
+
+Fixes adding authError query param in Passport adapter.
diff --git a/packages/blitz-auth/src/server/passport-adapter.ts b/packages/blitz-auth/src/server/passport-adapter.ts
index ccddce1ce9..27f5ea39e9 100644
--- a/packages/blitz-auth/src/server/passport-adapter.ts
+++ b/packages/blitz-auth/src/server/passport-adapter.ts
@@ -172,8 +172,10 @@ export function passportAuth(config: BlitzPassportConfig): ApiHandler {
               if (error) {
                 console.error(`Login via ${strategyName} was unsuccessful.`)
                 console.error(error)
+                
+                const authErrorQueryStringKey = redirectUrl.includes("?") ? "&authError=" : "?authError=";
                 redirectUrl +=
-                  "?authError=" + encodeURIComponent(truncateString(error.toString(), 100))
+                  authErrorQueryStringKey + encodeURIComponent(truncateString(error.toString(), 100))
                 res.setHeader("Location", redirectUrl)
                 res.statusCode = 302
                 res.end()