Failed to create certificate java.security.cert.CertificateException: Could not decode the client certificate. Please ensure that it is a base64 representation of a PKCS12 file: toDerInputStream rejects tag typ

Hi All,

Code - 

public class getAccessToken {
    public static void getToken() {
        HttpRequest request = new HttpRequest();
        HttpResponse response = new HttpResponse();
        Http http = new Http();
        // Set the request URL
        String authEndpoint = 'https://accounts.adp.com/auth/oauth/v2/token';
        request.setEndpoint(authEndpoint);
        // Set the request method
        request.setMethod('POST');
        // Set the request headers
        request.setHeader('Content-Type', 'application/x-www-form-urlencoded');
        // Set the request body
        String payload = 'grant_type=client_credentials' +
            '&client_id=437134191f47' +
            '&client_secret=49651ff0-70b6baac';
        request.setBody(payload);
        // Retrieve the AFHMutualSSLCert key file from static resource
        StaticResource staticResourceAFHMutualSSLCert = [SELECT Body FROM StaticResource WHERE Name = 'AFHMutualSSLCert'];
        String AFHMutualSSLCertContent = staticResourceAFHMutualSSLCert.Body.toString();
        system.debug('AFHMutualSSLCertContent: '+AFHMutualSSLCertContent);
        // Convert the AFHMutualSSLCertContent key to Base64-encoded string
        Blob AFHMutualSSLCertKeyBlob = Blob.valueOf(AFHMutualSSLCertContent);
        String AFHMutualSSLCertKeyBase64 = EncodingUtil.base64Encode(AFHMutualSSLCertKeyBlob);
        system.debug('AFHMutualSSLCertKeyBase64: '+AFHMutualSSLCertKeyBase64);
        // Retrieve the private key file from static resource
        StaticResource staticResourcePrivateKey = [SELECT Body FROM StaticResource WHERE Name = 'AFHPrivateKey'];
        String privateKeyContent = staticResourcePrivateKey.Body.toString();
        system.debug('privateKeyContent: '+privateKeyContent);
        // Convert the private key to Base64-encoded string
        Blob privateKeyBlob = Blob.valueOf(privateKeyContent);
        String privateKeyBase64 = EncodingUtil.base64Encode(privateKeyBlob);
        system.debug('privateKeyBase64: '+privateKeyBase64);
         request.setClientCertificate(AFHMutualSSLCertKeyBase64, privateKeyBase64);
        system.debug('request: '+request.getBody());
        // Send the request and get the response
        response = http.send(request);
        system.debug('response: '+response);
        // Parse the response
        if (response.getStatusCode() == 200) {
            // Successful response
            Map<String, Object> responseMap = (Map<String, Object>) JSON.deserializeUntyped(response.getBody());
            String accessToken = (String) responseMap.get('access_token');
            System.debug('Access Token: ' + accessToken);
            // Use the access token for further API requests
        } else {
            // Error handling for failed request
            System.debug('Error: ' + response.getBody());
        }
    }
}