diff --git a/testsuite/integration-arquillian/servers/auth-server/undertow/src/main/java/org/keycloak/testsuite/arquillian/undertow/lb/SimpleUndertowLoadBalancer.java b/testsuite/integration-arquillian/servers/auth-server/undertow/src/main/java/org/keycloak/testsuite/arquillian/undertow/lb/SimpleUndertowLoadBalancer.java
index 26be8f79ae..b27f8b5455 100644
--- a/testsuite/integration-arquillian/servers/auth-server/undertow/src/main/java/org/keycloak/testsuite/arquillian/undertow/lb/SimpleUndertowLoadBalancer.java
+++ b/testsuite/integration-arquillian/servers/auth-server/undertow/src/main/java/org/keycloak/testsuite/arquillian/undertow/lb/SimpleUndertowLoadBalancer.java
@@ -353,6 +353,7 @@ public class SimpleUndertowLoadBalancer {
 
         @Override
         public void couldNotResolveBackend(HttpServerExchange exchange) {
+            log.warnf("Could not resolve backend when request to: %s", exchange.getRequestURI());
             delegate.couldNotResolveBackend(exchange);
         }
 
diff --git a/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/OAuthClient.java b/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/OAuthClient.java
index 53d3f48eb8..c5bac639ca 100644
--- a/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/OAuthClient.java
+++ b/testsuite/integration-arquillian/tests/base/src/main/java/org/keycloak/testsuite/util/OAuthClient.java
@@ -19,6 +19,7 @@ package org.keycloak.testsuite.util;
 
 import org.apache.commons.io.IOUtils;
 import org.apache.commons.io.output.ByteArrayOutputStream;
+import org.apache.http.Header;
 import org.apache.http.NameValuePair;
 import org.apache.http.client.entity.UrlEncodedFormEntity;
 import org.apache.http.client.methods.CloseableHttpResponse;
@@ -958,8 +959,11 @@ public class OAuthClient {
         public AccessTokenResponse(CloseableHttpResponse response) throws Exception {
             try {
                 statusCode = response.getStatusLine().getStatusCode();
-                if (!"application/json".equals(response.getHeaders("Content-Type")[0].getValue())) {
-                    Assert.fail("Invalid content type");
+
+                Header[] contentTypeHeaders = response.getHeaders("Content-Type");
+                String contentType = (contentTypeHeaders != null && contentTypeHeaders.length > 0) ? contentTypeHeaders[0].getValue() : null;
+                if (!"application/json".equals(contentType)) {
+                    Assert.fail("Invalid content type. Status: " + statusCode + ", contentType: " + contentType);
                 }
 
                 String s = IOUtils.toString(response.getEntity().getContent());
diff --git a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/crossdc/ConcurrentLoginCrossDCTest.java b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/crossdc/ConcurrentLoginCrossDCTest.java
index 4cd02567d6..658a98b0f5 100644
--- a/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/crossdc/ConcurrentLoginCrossDCTest.java
+++ b/testsuite/integration-arquillian/tests/base/src/test/java/org/keycloak/testsuite/crossdc/ConcurrentLoginCrossDCTest.java
@@ -104,8 +104,10 @@ public class ConcurrentLoginCrossDCTest extends ConcurrentLoginTest {
                 int failureIndex = currentInvocarion / INVOCATIONS_BEFORE_SIMULATING_DC_FAILURE;
                 int dcToEnable = failureIndex % 2;
                 int dcToDisable = (failureIndex + 1) % 2;
-                suiteContext.getDcAuthServerBackendsInfo().get(dcToDisable).forEach(c -> loadBalancerCtrl.disableBackendNodeByName(c.getQualifier()));
+
+                // Ensure nodes from dcToEnable are available earlier then previous nodes from dcToDisable are disabled.
                 suiteContext.getDcAuthServerBackendsInfo().get(dcToEnable).forEach(c -> loadBalancerCtrl.enableBackendNodeByName(c.getQualifier()));
+                suiteContext.getDcAuthServerBackendsInfo().get(dcToDisable).forEach(c -> loadBalancerCtrl.disableBackendNodeByName(c.getQualifier()));
             }
         }
     }