diff --git a/CHANGELOG.md b/CHANGELOG.md
index db73aefd..661007d5 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,6 +4,7 @@ All notable changes to this project will be documented in this file. The format
 
 ## Table of Contents
 
+- [1.2.10 - 2025-09-16](#1210---2025-09-16)
 - [1.2.9 - 2025-09-07](#129---2025-09-07)
 - [1.2.8 - 2025-08-07](#128---2025-08-07)
 - [1.2.7 - 2025-08-05](#127---2025-08-05)
@@ -44,6 +45,15 @@ All notable changes to this project will be documented in this file. The format
 - [1.1.0 - 2024-08-19](#110---2024-08-19)
 - [1.0.0 - 2024-06-06](#100---2024-06-06)
 
+## [1.2.10] - 2025-09-16
+
+### Added
+- New error type `ErrHTTPServerFailedToAuthenticate` for authentication failures
+
+### Changed
+- Updated error return to include the new error type using `errors.Join()`
+- Replaced string-based error checking with proper `errors.Is()` type checking
+
 ## [1.2.9] - 2025-09-07
 
 ### Added
diff --git a/auth/clients/authhttp/authhttp.go b/auth/clients/authhttp/authhttp.go
index cbd16efe..b2b37875 100644
--- a/auth/clients/authhttp/authhttp.go
+++ b/auth/clients/authhttp/authhttp.go
@@ -435,7 +435,7 @@ func (a *AuthFetch) Fetch(ctx context.Context, urlStr string, config *Simplified
 					err  error
 				}{resp, retryErr}
 				return
-			} else if strings.Contains(err.Error(), "HTTP server failed to authenticate") {
+			} else if errors.Is(err, transports.ErrHTTPServerFailedToAuthenticate) {
 				// Fall back to regular HTTP request
 				resp, fallbackErr := a.handleFetchAndValidate(urlStr, config, peerToUse)
 				responseChan <- struct {
diff --git a/auth/transports/errors.go b/auth/transports/errors.go
index 4b599f2b..159e3b41 100644
--- a/auth/transports/errors.go
+++ b/auth/transports/errors.go
@@ -1,10 +1,13 @@
 // Package transports provides implementations of the auth.Transport interface
 package transports
 
-import "errors"
+import (
+	"errors"
+)
 
 // Common errors for all transports
 var (
 	// ErrNoHandlerRegistered is returned when trying to send a message without registering an OnData handler
-	ErrNoHandlerRegistered = errors.New("no OnData handler registered")
+	ErrNoHandlerRegistered            = errors.New("no OnData handler registered")
+	ErrHTTPServerFailedToAuthenticate = errors.New("HTTP server failed to authenticate")
 )
diff --git a/auth/transports/simplified_http_transport.go b/auth/transports/simplified_http_transport.go
index 21cba600..f6db2dbc 100644
--- a/auth/transports/simplified_http_transport.go
+++ b/auth/transports/simplified_http_transport.go
@@ -121,7 +121,7 @@ func (t *SimplifiedHTTPTransport) authMessageFromNonGeneralMessageResponse(resp
 
 	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
 		body, _ := io.ReadAll(resp.Body)
-		return responseMsg, fmt.Errorf("request failed with status %d: %s", resp.StatusCode, string(body))
+		return responseMsg, errors.Join(ErrHTTPServerFailedToAuthenticate, fmt.Errorf("request failed with status %d: %s", resp.StatusCode, string(body)))
 	}
 
 	if resp.ContentLength == 0 {