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Synchronous Function Execution Timed Out (408) on Appwrite Cloud – Dart Function

Jan 15, 2026, 19:00Last activity 8 months ago

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Ankit ManiyaOriginal post

Rank 3: Container

Jan 15, 2026, 18:52

Hi Appwrite team 👋

I’m facing a synchronous function execution timeout issue on Appwrite Cloud and would appreciate some guidance.

I executed this function using flutter appwrite sdk:
appwrite: 17.0.1

Error Message:

Plain text

Error Code: 408```
```Function Details:
Runtime: Dart (dart-3.5)
Function Type: HTTP-triggered
Method: POST
Plan: Free plan (Appwrite Cloud)
Resources:
CPU: 0.5
Memory: 512 MB
Configured Timeout: 15 seconds

Execution Info:
Status Code: 500
Status: Failed
Triggered By: HTTP
Actual Duration: ~30 seconds```

Summary

Function execution timed out after 30 seconds on Appwrite Cloud due to using synchronous function. Need to switch to asynchronous execution or ensure <30 sec duration.

Ankit Maniya

Rank 3: Container

Jan 15, 2026, 18:54

How I executed function from Flutter Application

@override
  Future<Uint8List?> sendByteData(Uint8List byteData) async {
    Uint8List? responseData;

    // Execute the function with the provided byte data
    // and return the response as byte data.
    //
    // To send base64-encoded data:
    // - Set Content-Type to 'text/plain'
    // - Use path: '/xxx?type=base64'
    // - Use body: base64Encode(byteData)
    //
    // To send binary data:
    // - Set Content-Type to 'application/octet-stream'
    // - Use path: '/xxx'
    // - Use body: String.fromCharCodes(byteData)

    await _functions
        .createExecution(
      functionId: _functionId,
      headers: {
        'Content-Type':
            'text/plain', // Use 'application/octet-stream' for binary data
      },
      path: '/xxx?type=base64', // Use '/xxx' for binary data
      method: ExecutionMethod.pOST,
      body: base64Encode(
          byteData), // Use String.fromCharCodes(byteData) for binary data
    )
        .then(
      (Execution execution) {
        // print('Execution MAP: => ${execution.toMap()}\n');
        print('[PORT-XXX] Function executed successfully: ${execution.responseBody}\n');

        // if it is not UnAuthorized response then responseData with byte data
        if (!execution.responseBody.contains('UnAuthorized')) {
          // When sending base64 data, the response is also base64-encoded
          responseData = base64Decode(execution.responseBody);
          
        }
      },
    ).onError((error, stackTrace) {
      throw "$error";
    });

    return responseData;
  }

Ankit Maniya

Rank 3: Container

Jan 15, 2026, 19:07

Error logs from my flutter app

I/flutter (21687): error, stackTrace :: 
I/flutter (21687): AppwriteException: function_synchronous_timeout, Synchronous function execution timed out. Use asynchronous execution instead, or ensure the execution duration doesn't exceed 30 seconds. (408), 
I/flutter (21687): #0      ClientMixin.prepareResponse (package:appwrite/src/client_mixin.dart:90:9)
client_mixin.dart:90
I/flutter (21687): #1      ClientIO.call (package:appwrite/src/client_io.dart:415:14)
client_io.dart:415
I/flutter (21687): <asynchronous suspension>
I/flutter (21687): #2      Functions.createExecution (package:appwrite/services/functions.dart:63:17)
functions.dart:63
I/flutter (21687): <asynchronous suspension>
I/flutter (21687): #3      DbBackendClient.sendByteData.<anonymous closure> (package:port_db_backend_client/db/db_client_flutter.dart:326:7)
db_client_flutter.dart:326
I/flutter (21687): <asynchronous suspension>
I/flutter (21687): #4      DbBackendClient.sendByteData (package:port_db_backend_client/db/db_client_flutter.dart:313:5)
db_client_flutter.dart:313
I/flutter (21687): <asynchronous suspension>
I/flutter (21687): #5      PortDbBackendClient.transportStatus.<anonymous closure> (package:port_db_backend_client/src/port_db_backend_client_base.dart:142:19)
port_db_backend_client_base.dart:142
I/flutter (21687): <asynchronous suspension>
I/flutter (21687): #6

Ankit Maniya

Rank 3: Container

Jan 15, 2026, 19:14

Here is the Screen Shots

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