diff --git a/src/Exceptions/ErrorException.php b/src/Exceptions/ErrorException.php
index 5f28481b..c6468592 100644
--- a/src/Exceptions/ErrorException.php
+++ b/src/Exceptions/ErrorException.php
@@ -14,12 +14,15 @@ final class ErrorException extends Exception
     /**
      * Creates a new Exception instance.
      *
-     * @param  array{message: string|array<int, string>, type: ?string, code: string|int|null}  $contents
+     * @param  array{message?: string|array<int, string>, type?: ?string, code?: string|int|null}|string  $contents
      */
-    public function __construct(private readonly array $contents, public readonly ResponseInterface $response)
+    public function __construct(private readonly string|array $contents, public readonly ResponseInterface $response)
     {
         $this->statusCode = $response->getStatusCode();
-        $message = ($contents['message'] ?: (string) $this->contents['code']) ?: 'Unknown error';
+
+        // Errors can be a string or an object with message, type, and code
+        $contents = is_string($contents) ? ['message' => $contents] : $contents;
+        $message = ($contents['message'] ?? null) ?: (string) ($contents['code'] ?? null) ?: 'Unknown error';
 
         if (is_array($message)) {
             $message = implode(PHP_EOL, $message);
@@ -51,7 +54,7 @@ public function getErrorMessage(): string
      */
     public function getErrorType(): ?string
     {
-        return $this->contents['type'];
+        return $this->contents['type'] ?? null;
     }
 
     /**
@@ -59,6 +62,6 @@ public function getErrorType(): ?string
      */
     public function getErrorCode(): string|int|null
     {
-        return $this->contents['code'];
+        return $this->contents['code'] ?? null;
     }
 }
diff --git a/src/Transporters/HttpTransporter.php b/src/Transporters/HttpTransporter.php
index 2a571f76..ee69e91e 100644
--- a/src/Transporters/HttpTransporter.php
+++ b/src/Transporters/HttpTransporter.php
@@ -162,7 +162,7 @@ private function throwIfJsonError(ResponseInterface $response, string|ResponseIn
         }
 
         try {
-            /** @var array{error?: array{message: string|array<int, string>, type: string, code: string}} $data */
+            /** @var array{error?: string|array{message: string|array<int, string>, type: string, code: string}} $data */
             $data = json_decode($contents, true, flags: JSON_THROW_ON_ERROR);
 
             if (isset($data['error'])) {
diff --git a/tests/Transporters/HttpTransporter.php b/tests/Transporters/HttpTransporter.php
index 688cf186..225ef0d1 100644
--- a/tests/Transporters/HttpTransporter.php
+++ b/tests/Transporters/HttpTransporter.php
@@ -190,6 +190,50 @@
         });
 })->with('request methods');
 
+test('error code may be string for no permission', function (string $requestMethod) {
+    $payload = Payload::create('completions', ['model' => 'gpt-42']);
+
+    $response = new Response(404, ['Content-Type' => 'application/json; charset=utf-8'], json_encode([
+        'error' => 'You have insufficient permissions for this operation. Missing scopes: api.model.read',
+    ]));
+
+    $this->client
+        ->shouldReceive('sendRequest')
+        ->once()
+        ->andReturn($response);
+
+    expect(fn () => $this->http->$requestMethod($payload))
+        ->toThrow(function (ErrorException $e) {
+            expect($e->getMessage())->toBe('You have insufficient permissions for this operation. Missing scopes: api.model.read')
+                ->and($e->getErrorMessage())->toBe('You have insufficient permissions for this operation. Missing scopes: api.model.read')
+                ->and($e->getErrorCode())->toBeNull()
+                ->and($e->getErrorType())->toBeNull();
+        });
+})->with('request methods');
+
+test('error code may have only message', function (string $requestMethod) {
+    $payload = Payload::create('completions', ['model' => 'gpt-42']);
+
+    $response = new Response(404, ['Content-Type' => 'application/json; charset=utf-8'], json_encode([
+        'error' => [
+            'message' => 'The engine is currently overloaded, please try again later',
+        ],
+    ]));
+
+    $this->client
+        ->shouldReceive('sendRequest')
+        ->once()
+        ->andReturn($response);
+
+    expect(fn () => $this->http->$requestMethod($payload))
+        ->toThrow(function (ErrorException $e) {
+            expect($e->getMessage())->toBe('The engine is currently overloaded, please try again later')
+                ->and($e->getErrorMessage())->toBe('The engine is currently overloaded, please try again later')
+                ->and($e->getErrorCode())->toBeNull()
+                ->and($e->getErrorType())->toBeNull();
+        });
+})->with('request methods');
+
 test('error type may be null on 429', function (string $requestMethod) {
     $payload = Payload::list('models');