diff --git a/app/config/errors.php b/app/config/errors.php
index f4439ff6ca..2e18f05797 100644
--- a/app/config/errors.php
+++ b/app/config/errors.php
@@ -578,6 +578,11 @@ return [
         'description' => 'The requested runtime is either inactive or unsupported. Please check the value of the _APP_FUNCTIONS_RUNTIMES environment variable.',
         'code' => 404,
     ],
+    Exception::FUNCTION_ALREADY_EXISTS => [
+        'name' => Exception::FUNCTION_ALREADY_EXISTS,
+        'description' => 'Function with the requested ID already exists. Try again with a different ID or use ID.unique() to generate a unique ID.',
+        'code' => 409,
+    ],
     Exception::FUNCTION_ENTRYPOINT_MISSING => [
         'name' => Exception::FUNCTION_ENTRYPOINT_MISSING,
         'description' => 'Entrypoint for your Appwrite Function is missing. Please specify it when making deployment or update the entrypoint under your function\'s "Settings" > "Configuration" > "Entrypoint".',
diff --git a/src/Appwrite/Extend/Exception.php b/src/Appwrite/Extend/Exception.php
index 61169685c4..6f8744568a 100644
--- a/src/Appwrite/Extend/Exception.php
+++ b/src/Appwrite/Extend/Exception.php
@@ -164,6 +164,7 @@ class Exception extends \Exception
 
     /** Functions */
     public const string FUNCTION_NOT_FOUND = 'function_not_found';
+    public const string FUNCTION_ALREADY_EXISTS = 'function_already_exists';
     public const string FUNCTION_RUNTIME_UNSUPPORTED = 'function_runtime_unsupported';
     public const string FUNCTION_ENTRYPOINT_MISSING = 'function_entrypoint_missing';
     public const string FUNCTION_SYNCHRONOUS_TIMEOUT = 'function_synchronous_timeout';
diff --git a/src/Appwrite/Platform/Modules/Functions/Http/Functions/Create.php b/src/Appwrite/Platform/Modules/Functions/Http/Functions/Create.php
index b00a2ad2bf..932f515fc1 100644
--- a/src/Appwrite/Platform/Modules/Functions/Http/Functions/Create.php
+++ b/src/Appwrite/Platform/Modules/Functions/Http/Functions/Create.php
@@ -23,6 +23,7 @@ use Utopia\Config\Config;
 use Utopia\Database\Database;
 use Utopia\Database\DateTime;
 use Utopia\Database\Document;
+use Utopia\Database\Exception\Duplicate as DuplicateException;
 use Utopia\Database\Helpers\ID;
 use Utopia\Database\Helpers\Permission;
 use Utopia\Database\Helpers\Role;
@@ -201,36 +202,40 @@ class Create extends Base
             throw new Exception(Exception::GENERAL_ARGUMENT_INVALID, 'When connecting to VCS (Version Control System), you need to provide "installationId" and "providerBranch".');
         }
 
-        $function = $dbForProject->createDocument('functions', new Document([
-            '$id' => $functionId,
-            'execute' => $execute,
-            'enabled' => $enabled,
-            'live' => true,
-            'logging' => $logging,
-            'name' => $name,
-            'runtime' => $runtime,
-            'deploymentInternalId' => '',
-            'deploymentId' => '',
-            'events' => $events,
-            'schedule' => $schedule,
-            'scheduleInternalId' => '',
-            'scheduleId' => '',
-            'timeout' => $timeout,
-            'entrypoint' => $entrypoint,
-            'commands' => $commands,
-            'scopes' => $scopes,
-            'search' => implode(' ', [$functionId, $name, $runtime]),
-            'version' => 'v5',
-            'installationId' => $installation->getId(),
-            'installationInternalId' => $installation->getSequence(),
-            'providerRepositoryId' => $providerRepositoryId,
-            'repositoryId' => '',
-            'repositoryInternalId' => '',
-            'providerBranch' => $providerBranch,
-            'providerRootDirectory' => $providerRootDirectory,
-            'providerSilentMode' => $providerSilentMode,
-            'specification' => $specification
-        ]));
+        try {
+            $function = $dbForProject->createDocument('functions', new Document([
+                '$id' => $functionId,
+                'execute' => $execute,
+                'enabled' => $enabled,
+                'live' => true,
+                'logging' => $logging,
+                'name' => $name,
+                'runtime' => $runtime,
+                'deploymentInternalId' => '',
+                'deploymentId' => '',
+                'events' => $events,
+                'schedule' => $schedule,
+                'scheduleInternalId' => '',
+                'scheduleId' => '',
+                'timeout' => $timeout,
+                'entrypoint' => $entrypoint,
+                'commands' => $commands,
+                'scopes' => $scopes,
+                'search' => implode(' ', [$functionId, $name, $runtime]),
+                'version' => 'v5',
+                'installationId' => $installation->getId(),
+                'installationInternalId' => $installation->getSequence(),
+                'providerRepositoryId' => $providerRepositoryId,
+                'repositoryId' => '',
+                'repositoryInternalId' => '',
+                'providerBranch' => $providerBranch,
+                'providerRootDirectory' => $providerRootDirectory,
+                'providerSilentMode' => $providerSilentMode,
+                'specification' => $specification
+            ]));
+        } catch (DuplicateException) {
+            throw new Exception(Exception::FUNCTION_ALREADY_EXISTS);
+        }
 
         $schedule = Authorization::skip(
             fn () => $dbForPlatform->createDocument('schedules', new Document([
diff --git a/tests/e2e/Services/Functions/FunctionsCustomClientTest.php b/tests/e2e/Services/Functions/FunctionsCustomClientTest.php
index f8b7bae325..c3c9fbfbab 100644
--- a/tests/e2e/Services/Functions/FunctionsCustomClientTest.php
+++ b/tests/e2e/Services/Functions/FunctionsCustomClientTest.php
@@ -32,6 +32,41 @@ class FunctionsCustomClientTest extends Scope
             'timeout' => 10,
         ]);
         $this->assertEquals(401, $function['headers']['status-code']);
+
+
+        /**
+         * Test for DUPLICATE functionId
+         */
+        $functionId = $this->setupFunction([
+            'functionId' => ID::unique(),
+            'name' => 'Test',
+            'execute' => [Role::user($this->getUser()['$id'])->toString()],
+            'runtime' => 'node-22',
+            'entrypoint' => 'index.js',
+            'events' => [
+                'users.*.create',
+                'users.*.delete',
+            ],
+            'timeout' => 10,
+        ]);
+
+        $response = $this->client->call(Client::METHOD_POST, '/functions', array_merge([
+            'content-type' => 'application/json',
+            'x-appwrite-project' => $this->getProject()['$id'],
+            'x-appwrite-key' => $this->getProject()['apiKey'],
+        ]), [
+            'functionId' => $functionId,
+            'name' => 'Test',
+            'execute' => [Role::user($this->getUser()['$id'])->toString()],
+            'runtime' => 'node-22',
+            'entrypoint' => 'index.js',
+            'events' => [
+                'users.*.create',
+                'users.*.delete',
+            ],
+            'timeout' => 10,
+        ]);
+        $this->assertEquals(409, $response['headers']['status-code']);
     }
 
     public function testCreateExecution()