System.CalloutException: Callout from scheduled Apex not supported

We used to get “System.CalloutException: Callout from scheduled Apex not supported” Error when we are making a web service callout from a class which is implementing Database.Schedulable interface because Salesforce does not allow us to make callouts from Schedulable classes.

Sample Scheduler Class

global class SampleScheduler implements Schedulable{
    
    global void execute(SchedulableContext sc) 
    {        
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        request.setEndpoint('https://th-apex-http-callout.herokuapp.com/animals');
        request.setMethod('GET');
        HttpResponse response = http.send(request);

        if (response.getStatusCode() == 200) {
            Map<String, Object> results = (Map<String, Object>) JSON.deserializeUntyped(response.getBody());
            List<Object> animals = (List<Object>) results.get('animals');
            System.debug('Received the following animals:');
            for (Object animal: animals) {
                System.debug(animal);
            }
        }
    }    
}

Error Screen Shot

Scheduler: failed to execute scheduled job: jobId: 7076A00000EmLPu, class: common.apex.async.AsyncApexJobObject, reason: Callout from scheduled Apex not supported

Solution:- We can solved this issue with below solution.

1. @future method : A future runs as asynchronously. You can call a future method for executing long-running operations, such as callouts to external Web services or any operation you’d like to run in its own thread, on its own time

Learn more about the Future method.

Scheduler Class

global class SampleScheduler implements Schedulable{
    
    global void execute(SchedulableContext sc) 
    {        
 
      BatchUtilClass.futureMethodSample();
    }    
}

Future Class Method

public class BatchUtilClass {
    @future(callout=true)
    public static void futureMethodSample() {
        Http http = new Http();
        HttpRequest request = new HttpRequest();
        request.setEndpoint('https://th-apex-http-callout.herokuapp.com/animals');
        request.setMethod('GET');
        HttpResponse response = http.send(request);

        if (response.getStatusCode() == 200) {
            Map<String, Object> results = (Map<String, Object>) JSON.deserializeUntyped(response.getBody());
            List<Object> animals = (List<Object>) results.get('animals');
            System.debug('Received the following animals:');
            for (Object animal: animals) {
                System.debug(animal);
            }
        }
    }
}

Learn about Different types of Exceptions in Salesforce.

Summary

Alternatively, we can also use a Queueable class that implements a database.AllowsCallouts interface to do callouts.