Simple Apex controller function never executing

Question

I have a standard Aura Lightning Component with onChange handler, Javascript controller and Apex controller but even though everything seems to be fine, the server controller method is never called.

The lightning component handler:

<aura:handler name="change" value="{!v.contact.AccountId}" action="{!c.autoConsBP}"/>

and Javascript controller method:

autoConsBP: function (component, event, helper) {
        var id = component.get("v.contact.AccountId");
        var action = component.get("c.populateConsBPField");
        action.setParams({
            "accountId": id
        });
        action.setCallback(this, function (response) {
            var state = response.getState();
            if (state === "SUCCESS") {
                console.log('Returned value: ' + response.getReturnValue());
            }
            if (state === "ERROR") {
                console.log('Error');
            }
        });
        $A.enqueueAction(action);
    }

in Apex controller there is a method populateConsBPField(String accountId):

    @AuraEnabled
    public static List<String> populateConsBPField(String accountId) {
        System.debug('Entering');
        Account fromAccount = [Select Id, Consolidated_Business_Partner__c, Consolidated_Business_Partner__r.Name from Account where Id = :accountId];
        System.debug('Account: '+ fromAccount);
        List<String> consBP = new List<String>();
        consBP.add(fromAccount.Consolidated_Business_Partner__c);
        consBP.add(fromAccount.Consolidated_Business_Partner__r.Name);
        System.debug('Leaving');
        return consBP;
    }

No matter what I do, the callback function always returns Error. What is also strange - logs indicate that my function is never even called:

18:33:49.0 (513471)|EXECUTION_STARTED
18:33:49.0 (519142)|CODE_UNIT_STARTED|[EXTERNAL]|Aura
18:33:49.0 (1662266)|CODE_UNIT_FINISHED|Aura
18:33:49.0 (2851055)|EXECUTION_FINISHED

This is everything the logs are saying but when I use Anyonymous Apex to call my function:

System.debug(msContactController.populateConsBPField('0011X00000G7KAwQAN'));

I get proper result that I would be expecting also when calling the Apex Controller from Lightning component:

18:35:21.58 (73544969)|USER_DEBUG|[71]|DEBUG|Entering
18:35:21.58 (95366704)|USER_DEBUG|[73]|DEBUG|Account: Account:{Id=0011X00000G7KAwQAN, Consolidated_Business_Partner__c=0011X00000G7Ju5QAF}
18:35:21.58 (95717963)|USER_DEBUG|[77]|DEBUG|Leaving
18:35:21.58 (95768752)|USER_DEBUG|[2]|DEBUG|(0011X00000G7Ju5QAF, Test ConsBP)

I have no idea why the server controller function might not be called by JS controller. The action is enqueued properly and the callback is still always resulting in error state. Why is this happening?

Answer 1

Using sdandamud1 suggestion I added debugging to the main JS method:

var errormsg = response.getError()[0].message;
console.log(errormsg);

And it showed: Value provided is invalid for action parameter 'accountId' of type 'String' It turns out that in my Aura Component I was using lightning:recordEditForm as the input for AccountID and the value was being sent as an array!

I my JS controller I just needed to retrieve the value from the array and it worked:

var id = component.get("v.contact.AccountId")[0];