Basic GET request not working with name credential

Question

I have a GET request I want to manage but Authorization Header is not working if I retrieve username and password from Named Credential.

String username = '{!$Credential.UserName}';
String password = '{!$Credential.Password}';
request.setEndpoint('callout:NamedCredential/scan/' + EncodingUtil.urlEncode(customMetadataLIST[0].AccessCode__c, 'UTF-8'));
request.setHeader('Authorization', 'Basic ' + EncodingUtil.base64Encode(Blob.valueOf(username + ':' + password)));

If I put username and password directly is working fine and I don't know what am I doing wrong.

Answer 1

Check the "Generate Authorization Header" on the Named Credential, and Salesforce will do it for you automatically, no setHeader method call required.

Alternatively, just set the following value:

request.setHeader('Authorization', '{!$Credential.AuthorizationHeaderValue}');

It will automatically generate the correct Basic encodedusername:encodedpassword for you.