diff --git a/.swagger-codegen-ignore b/.swagger-codegen-ignore
index a93e7b0..91471a5 100644
--- a/.swagger-codegen-ignore
+++ b/.swagger-codegen-ignore
@@ -40,6 +40,5 @@ autoload.php
 phpunit.xml.dist
 docs/
 test/
-src/ApiClient.php
 src/ApiException.php
-src/Client/
+src/Client/Auth/**
diff --git a/CHANGELOG.md b/CHANGELOG.md
index ecba5a0..f1723d0 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,7 +1,12 @@
 # DocuSign Admin Java Client Changelog
 See [DocuSign Support Center](https://support.docusign.com/en/releasenotes/) for Product Release Notes.
 
-## [v2.1.0] - Admin API v2.1-1.4.3 - 2026-03-05
+## [v2.1.1] - Admin API v2.1-1.4.3 - 2026-06-09
+### Changed
+- Added support for version v2.1-26.1.1.00 of the DocuSign ESignature API.
+- Updated the SDK release version.
+
+## [v2.1.0] - Admin API v2.1-1.4.3 - 2026-03-09
 ### Changed
 - Added support for version v2.1-1.4.3 of the DocuSign Admin API.
 - Updated the SDK release version.
diff --git a/composer.json b/composer.json
index 43c396a..20dc86c 100644
--- a/composer.json
+++ b/composer.json
@@ -21,7 +21,7 @@
         "ext-curl": "*",
         "ext-json": "*",
         "ext-mbstring": "*",
-        "firebase/php-jwt": "^6.0"
+        "adhocore/jwt": "^1.1"
     },
     "require-dev": {
         "phpunit/phpunit": "~4.8",
diff --git a/src/Api/BulkExportsApi.php b/src/Api/BulkExportsApi.php
index 7e7ffbc..a8994b8 100644
--- a/src/Api/BulkExportsApi.php
+++ b/src/Api/BulkExportsApi.php
@@ -116,7 +116,7 @@ public function updateResourcePath(string $resourcePath, string $baseName, strin
     /**
      * Operation createAccountSettingsExport
      *
-     * Creates a  new Account Setting Export request.
+     * Creates a new Account Setting Export request.
      *
      * @param ?string $organization_id The organization ID Guid
      * @param \DocuSign\Admin\Model\OrganizationAccountsRequest $request Request body containing details about the accounts be compared (required)
@@ -133,7 +133,7 @@ public function createAccountSettingsExport($organization_id, $request)
     /**
      * Operation createAccountSettingsExportWithHttpInfo
      *
-     * Creates a  new Account Setting Export request.
+     * Creates a new Account Setting Export request.
      *
      * @param ?string $organization_id The organization ID Guid
      * @param \DocuSign\Admin\Model\OrganizationAccountsRequest $request Request body containing details about the accounts be compared (required)
diff --git a/src/Client/ApiClient.php b/src/Client/ApiClient.php
index 24a2a4c..f820ac7 100644
--- a/src/Client/ApiClient.php
+++ b/src/Client/ApiClient.php
@@ -1,8 +1,9 @@
 <?php
+
 /**
  * ApiClient
  *
- * PHP version 5
+ * PHP version 7.4
  *
  * @category Class
  * @package  DocuSign\Admin
@@ -11,13 +12,14 @@
  */
 
 /**
- * DocuSign REST API
+ * Docusign Admin API
  *
- * The DocuSign REST API provides you with a powerful, convenient, and simple Web services API for interacting with DocuSign.
+ * An API for an organization administrator to manage organizations, accounts and users
  *
  * OpenAPI spec version: v2.1
  * Contact: devcenter@docusign.com
  * Generated by: https://github.com/swagger-api/swagger-codegen.git
+ * Swagger Codegen version: 2.4.21
  */
 
 /**
@@ -32,15 +34,15 @@
 use \DocuSign\Admin\Configuration;
 use \DocuSign\Admin\ObjectSerializer;
 use SebastianBergmann\RecursionContext\InvalidArgumentException;
-use Firebase\JWT\JWT;
-
+use Ahc\Jwt\JWT;
 
 /**
  * ApiClient Class Doc Comment
  *
  * @category Class
  * @package  DocuSign\Admin
- * @author   Swagger Codegen team
+ * @author   Swagger Codegen team <apihelp@docusign.com>
+ * @license  The Docusign PHP Client SDK is licensed under the MIT License.
  * @link     https://github.com/swagger-api/swagger-codegen
  */
 class ApiClient
@@ -53,8 +55,6 @@ class ApiClient
     public static $PUT = "PUT";
     public static $DELETE = "DELETE";
 
-
-
     public static $SCOPE_SIGNATURE = "signature";
     public static $SCOPE_EXTENDED = "extended";
     public static $SCOPE_IMPERSONATION = "impersonation";
@@ -88,7 +88,7 @@ class ApiClient
      * @param Configuration $config Rest API config for this ApiClient
      * @param OAuth $oAuth OAuth config for this ApiClient
      */
-    public function __construct(Configuration $config = null, OAuth $oAuth = null)
+    public function __construct(?Configuration $config = null, ?OAuth $oAuth = null)
     {
         if ($config === null) {
             $config = Configuration::getDefaultConfiguration();
@@ -170,14 +170,14 @@ public function getApiKeyWithPrefix($apiKeyIdentifier)
      * @param string $endpointPath path to method endpoint before expanding parameters
      * @param bool   $oAuth        pass true in case of oAuth requests
      *
-     * @throws ApiException on a non 2xx response
+     * @throws DocuSign\Admin\Client\ApiException on a non 2xx response
      * @return mixed
      */
     public function callApi($resourcePath, $method, $queryParams, $postData, $headerParams, $responseType = null, $endpointPath = null, $oAuth = false)
     {
         $headers = [];
 
-        // DocuSign: Add DocuSign tracking headers
+        // Docusign: Add Docusign tracking headers
         $this->config->addDefaultHeader("X-DocuSign-SDK", "PHP");
 
         $url = $this->config->getHost() . $resourcePath;
@@ -202,7 +202,7 @@ public function callApi($resourcePath, $method, $queryParams, $postData, $header
             $postData = json_encode(ObjectSerializer::sanitizeForSerialization($postData));
         }
 
-        if (in_array("Content-Type: multipart/form-data", $headers, true))
+        if (in_array('Content-Type: multipart/form-data', $headers, true))
         {            
             foreach($postData as $property => $value)
             {
@@ -220,11 +220,12 @@ public function callApi($resourcePath, $method, $queryParams, $postData, $header
         if ($this->config->getCurlTimeout() !== 0) {
             curl_setopt($curl, CURLOPT_TIMEOUT, $this->config->getCurlTimeout());
         }
+
         // set connect timeout, if needed
         if ($this->config->getCurlConnectTimeout() != 0) {
             curl_setopt($curl, CURLOPT_CONNECTTIMEOUT, $this->config->getCurlConnectTimeout());
         }
-
+        
         // return the result on success, rather than just true
         curl_setopt($curl, CURLOPT_RETURNTRANSFER, true);
 
@@ -333,15 +334,17 @@ public function callApi($resourcePath, $method, $queryParams, $postData, $header
             }
         } else {
             $data = json_decode($http_body);
+            $serializedData = $data;
             if (json_last_error() > 0) { // if response is a string
                 $data = $http_body;
             }
-            if(is_object($data)){
-                $data = serialize($data);
+
+            if(is_object($serializedData)){
+                $serializedData = serialize($serializedData);
             }
 
             throw new ApiException(
-                "Error while requesting server, received a non successful HTTP code [".$response_info['http_code']."] with response Body:  $data",
+                "Error while requesting server, received a non successful HTTP code [".$response_info['http_code']."] with response Body:  $serializedData",
                 $response_info['http_code'],
                 $http_header,
                 $data
@@ -428,7 +431,7 @@ protected function httpParseHeaders($raw_headers)
     /**
      * Helper method to configure the OAuth accessCode/implicit flow parameters
      *
-     * @param string $client_id DocuSign OAuth Client Id(AKA Integrator Key)
+     * @param string $client_id Docusign OAuth Client Id(AKA Integrator Key)
      * @param string|array $scopes the list of requested scopes.  Client applications may be scoped to a limited set of system access.
      * @param string $redirect_uri This determines where to deliver the response containing the authorization code
      * @param string $response_type Determines the response type of the authorization request, NOTE: these response types are
@@ -464,8 +467,8 @@ public function getAuthorizationURI($client_id, $scopes, $redirect_uri, $respons
     /**
      * GenerateAccessToken will exchange the authorization code for an access token and refresh tokens.
      *
-     * @param string $client_id DocuSign OAuth Client Id(AKA Integrator Key)
-     * @param string $client_secret The secret key you generated when you set up the integration in DocuSign Admin console.
+     * @param string $client_id Docusign OAuth Client Id(AKA Integrator Key)
+     * @param string $client_secret The secret key you generated when you set up the integration in Docusign Admin console.
      * @param string $code The authorization code
      *
      * @return array
@@ -477,7 +480,7 @@ public function generateAccessToken($client_id = null, $client_secret = null, $c
         if (!$client_id) {
             throw new \InvalidArgumentException('Missing the required parameter $client_id when calling generateAccessToken');
         }
-        if (!$client_secret || !$code) {
+        if (!$client_secret) {
             throw new \InvalidArgumentException('Missing the required parameter $client_secret when calling generateAccessToken');
         }
         if (!$code) {
@@ -500,11 +503,50 @@ public function generateAccessToken($client_id = null, $client_secret = null, $c
             $this->config->addDefaultHeader("Authorization", "{$response->token_type} {$response->access_token}");
         return [$this->getSerializer()->deserialize($response, '\DocuSign\Admin\Client\Auth\OAuthToken', $httpHeader), $statusCode, $httpHeader];
     }
+    
+    /**
+     * Refresh Access Token
+     *
+     * @param string $client_id Docusign OAuth Client Id(AKA Integrator Key)
+     * @param string $client_secret The secret key you generated when you set up the integration in Docusign Admin console.
+     * @param string $code The authorization code
+     *
+     * @return array
+     * @throws ApiException
+     * @throws InvalidArgumentException
+     */
+    public function refreshAccessToken($client_id = null, $client_secret = null, $refresh_token = null)
+    { 
+        if (!$client_id) { 
+            throw new \InvalidArgumentException('Missing the required parameter $client_id when calling refreshAccessToken'); 
+        } 
+        if (!$client_secret) { 
+            throw new \InvalidArgumentException('Missing the required parameter $client_secret when calling refreshAccessToken'); 
+        } 
+        if (!$refresh_token) { 
+            throw new \InvalidArgumentException('Missing the required parameter $refresh_token when calling refreshAccessToken'); 
+        }
+        $resourcePath = "/oauth/token"; 
+        $queryParams = []; 
+        $integrator_and_secret_key = "Basic " . utf8_decode(base64_encode("{$client_id}:{$client_secret}")); 
+        $headers = [ 
+            "Authorization" => $integrator_and_secret_key, 
+            "Content-Type" => "application/x-www-form-urlencoded", 
+        ];
+        $postData = [ 
+            "grant_type" => "refresh_token", 
+            "refresh_token" => $refresh_token, 
+        ];
+        list($response, $statusCode, $httpHeader) = $this->callApi($resourcePath, self::$POST, $queryParams, $postData, $headers, null, null, true);
+        if (isset($response->access_token))  
+            $this->config->addDefaultHeader("Authorization", "{$response->token_type} {$response->access_token}");  
+        return [$this->getSerializer()->deserialize($response, '\DocuSign\Admin\Client\Auth\OAuthToken', $httpHeader), $statusCode, $httpHeader]; 
+    }
 
     /**
      * Request JWT User Token
      *
-     * @param  string $client_id DocuSign OAuth Client Id(AKA Integrator Key)
+     * @param  string $client_id Docusign OAuth Client Id(AKA Integrator Key)
      * @param  string $rsa_private_key the RSA private key
      * @param  string|string[] $scopes array optional The list of requested scopes may include (but not limited to) You can also pass any advanced scope.
      * @param  string $user_id
@@ -543,7 +585,15 @@ public function requestJWTUserToken($client_id, $user_id, $rsa_private_key, $sco
             "scope" => is_array($scopes)?implode(" ", $scopes): $scopes
         ];
 
-        $jwt = JWT::encode($claim, $rsa_private_key, 'RS256');
+        $private_key = openssl_pkey_get_private($rsa_private_key);
+        if ($private_key === false && is_file($rsa_private_key)) {
+            $private_key = openssl_pkey_get_private('file://' . $rsa_private_key);
+        }
+        if ($private_key === false) {
+            throw new \InvalidArgumentException('Invalid RSA private key provided when calling requestJWTUserToken');
+        }
+
+        $jwt = (new JWT($private_key, 'RS256'))->encode($claim);
 
         $resourcePath = "/oauth/token";
         $queryParams = [];
@@ -565,7 +615,7 @@ public function requestJWTUserToken($client_id, $user_id, $rsa_private_key, $sco
     /**
      * Request JWT Application Token
      *
-     * @param string $client_id DocuSign OAuth Client Id(AKA Integrator Key)
+     * @param string $client_id Docusign OAuth Client Id(AKA Integrator Key)
      * @param string $rsa_private_key the RSA private key
      * @param string|string[] $scopes array optional The list of requested scopes may include (but not limited to) You can also pass any advanced scope.
      * @param int $expires_in int Number of minutes token will be valid
@@ -599,7 +649,15 @@ public function requestJWTApplicationToken($client_id, $rsa_private_key, $scopes
             "scope" => is_array($scopes)?implode(" ", $scopes):$scopes
         ];
 
-        $jwt = JWT::encode($claim, $rsa_private_key, 'RS256');
+        $private_key = openssl_pkey_get_private($rsa_private_key);
+        if ($private_key === false && is_file($rsa_private_key)) {
+            $private_key = openssl_pkey_get_private('file://' . $rsa_private_key);
+        }
+        if ($private_key === false) {
+            throw new \InvalidArgumentException('Invalid RSA private key provided when calling requestJWTApplicationToken');
+        }
+
+        $jwt = (new JWT($private_key, 'RS256'))->encode($claim);
 
         $resourcePath = "/oauth/token";
         $queryParams = [];
@@ -654,4 +712,4 @@ public function getUserInfo($access_token)
             $httpHeader
         ];
     }
-}
+}
\ No newline at end of file
diff --git a/src/Configuration.php b/src/Configuration.php
index b7f294f..2496bcb 100644
--- a/src/Configuration.php
+++ b/src/Configuration.php
@@ -111,7 +111,7 @@ class Configuration
      *
      * @var string
      */
-    protected $userAgent = 'Swagger-Codegen/v2.1/2.1.0/php/' . PHP_VERSION;
+    protected $userAgent = 'Swagger-Codegen/v2.1/2.1.1/php/' . PHP_VERSION;
 
     /**
      * Debug switch (default set to false)
@@ -774,7 +774,7 @@ public static function toDebugReport()
         $report .= '    OS: ' . php_uname() . PHP_EOL;
         $report .= '    PHP Version: ' . PHP_VERSION . PHP_EOL;
         $report .= '    OpenAPI Spec Version: v2.1' . PHP_EOL;
-        $report .= '    SDK Package Version: 2.1.0' . PHP_EOL;
+        $report .= '    SDK Package Version: 2.1.1' . PHP_EOL;
         $report .= '    Temp Folder Path: ' . self::getDefaultConfiguration()->getTempFolderPath() . PHP_EOL;
 
         return $report;
diff --git a/src/Model/UpdateUsersRequest.php b/src/Model/UpdateUsersRequest.php
index aec571f..dc39883 100644
--- a/src/Model/UpdateUsersRequest.php
+++ b/src/Model/UpdateUsersRequest.php
@@ -59,7 +59,8 @@ class UpdateUsersRequest implements ModelInterface, ArrayAccess
       * @var string[]
       */
     protected static $swaggerTypes = [
-        'users' => '\DocuSign\Admin\Model\UpdateUserRequest[]'
+        'users' => '\DocuSign\Admin\Model\UpdateUserRequest[]',
+        'auto_activate_memberships_on_reactivation' => '?bool'
     ];
 
     /**
@@ -68,7 +69,8 @@ class UpdateUsersRequest implements ModelInterface, ArrayAccess
       * @var string[]
       */
     protected static $swaggerFormats = [
-        'users' => null
+        'users' => null,
+        'auto_activate_memberships_on_reactivation' => null
     ];
 
     /**
@@ -98,7 +100,8 @@ public static function swaggerFormats()
      * @var string[]
      */
     protected static $attributeMap = [
-        'users' => 'users'
+        'users' => 'users',
+        'auto_activate_memberships_on_reactivation' => 'auto_activate_memberships_on_reactivation'
     ];
 
     /**
@@ -107,7 +110,8 @@ public static function swaggerFormats()
      * @var string[]
      */
     protected static $setters = [
-        'users' => 'setUsers'
+        'users' => 'setUsers',
+        'auto_activate_memberships_on_reactivation' => 'setAutoActivateMembershipsOnReactivation'
     ];
 
     /**
@@ -116,7 +120,8 @@ public static function swaggerFormats()
      * @var string[]
      */
     protected static $getters = [
-        'users' => 'getUsers'
+        'users' => 'getUsers',
+        'auto_activate_memberships_on_reactivation' => 'getAutoActivateMembershipsOnReactivation'
     ];
 
     /**
@@ -180,6 +185,7 @@ public function getModelName()
     public function __construct(?array $data = null)
     {
         $this->container['users'] = isset($data['users']) ? $data['users'] : null;
+        $this->container['auto_activate_memberships_on_reactivation'] = isset($data['auto_activate_memberships_on_reactivation']) ? $data['auto_activate_memberships_on_reactivation'] : null;
     }
 
     /**
@@ -229,6 +235,30 @@ public function setUsers($users)
 
         return $this;
     }
+
+    /**
+     * Gets auto_activate_memberships_on_reactivation
+     *
+     * @return ?bool
+     */
+    public function getAutoActivateMembershipsOnReactivation()
+    {
+        return $this->container['auto_activate_memberships_on_reactivation'];
+    }
+
+    /**
+     * Sets auto_activate_memberships_on_reactivation
+     *
+     * @param ?bool $auto_activate_memberships_on_reactivation When set to **true**, the user's memberships will be automatically activated on reactivation.
+     *
+     * @return $this
+     */
+    public function setAutoActivateMembershipsOnReactivation($auto_activate_memberships_on_reactivation)
+    {
+        $this->container['auto_activate_memberships_on_reactivation'] = $auto_activate_memberships_on_reactivation;
+
+        return $this;
+    }
     /**
      * Returns true if offset exists. False otherwise.
      *