diff --git a/app/api/exceptions.py b/app/api/exceptions.py
index 3a5a679f..6911cf91 100644
--- a/app/api/exceptions.py
+++ b/app/api/exceptions.py
@@ -1,5 +1,5 @@
 from rest_framework import status
-from rest_framework.exceptions import APIException, PermissionDenied
+from rest_framework.exceptions import APIException, PermissionDenied, NotFound, ValidationError
 
 
 class FileParseException(APIException):
@@ -20,3 +20,11 @@ class AutoLabelingException(APIException):
 class AutoLabeliingPermissionDenied(PermissionDenied):
     default_detail = 'You do not have permission to perform auto labeling.' \
                      'Please ask the project administrators to add you.'
+
+
+class URLConnectionError(NotFound):
+    default_detail = 'Failed to establish a connection. Please check the URL or network.'
+
+
+class AWSTokenError(ValidationError):
+    default_detail = 'The security token included in the request is invalid.'
diff --git a/app/api/serializers.py b/app/api/serializers.py
index 05056031..e07d693e 100644
--- a/app/api/serializers.py
+++ b/app/api/serializers.py
@@ -268,5 +268,11 @@ class AutoLabelingConfigSerializer(serializers.ModelSerializer):
         try:
             RequestModelFactory.create(data['model_name'], data['model_attrs'])
         except Exception:
-            raise serializers.ValidationError('The attributes does not match the model.')
+            model = RequestModelFactory.find(data['model_name'])
+            schema = model.schema()
+            required_fields = ', '.join(schema['required']) if 'required' in schema else ''
+            raise serializers.ValidationError(
+                'The attributes does not match the model.'
+                'You need to correctly specify the required fields: {}'.format(required_fields)
+            )
         return data
diff --git a/app/api/views.py b/app/api/views.py
index ad73dfcd..8cda27c7 100644
--- a/app/api/views.py
+++ b/app/api/views.py
@@ -2,6 +2,8 @@ import collections
 import json
 import random
 
+import botocore.exceptions
+import requests
 from auto_labeling_pipeline.menu import Options
 from auto_labeling_pipeline.models import RequestModelFactory
 from auto_labeling_pipeline.mappings import MappingTemplate
@@ -25,7 +27,7 @@ from rest_framework.views import APIView
 from rest_framework.parsers import MultiPartParser
 from rest_framework_csv.renderers import CSVRenderer
 
-from .exceptions import AutoLabelingException, AutoLabeliingPermissionDenied
+from .exceptions import AutoLabelingException, AutoLabeliingPermissionDenied, URLConnectionError, AWSTokenError
 from .filters import DocumentFilter
 from .models import Project, Label, Document, RoleMapping, Role, Comment, AutoLabelingConfig
 from .permissions import IsProjectAdmin, IsAnnotatorAndReadOnly, IsAnnotator, IsAnnotationApproverAndReadOnly, IsOwnAnnotation, IsAnnotationApprover, IsOwnComment
@@ -541,11 +543,12 @@ class AutoLabelingConfigTest(APIView):
                 data={'valid': True, 'labels': output},
                 status=status.HTTP_200_OK
             )
+        except requests.exceptions.ConnectionError:
+            raise URLConnectionError()
+        except botocore.exceptions.ClientError:
+            raise AWSTokenError()
         except Exception as e:
-            return Response(
-                data={'valid': False},
-                status=status.HTTP_400_BAD_REQUEST
-            )
+            raise e
 
     def pass_config_validation(self):
         config = self.request.data['config']
diff --git a/frontend/components/containers/settings/ConfigCreationForm.vue b/frontend/components/containers/settings/ConfigCreationForm.vue
index f64a151b..c5461067 100644
--- a/frontend/components/containers/settings/ConfigCreationForm.vue
+++ b/frontend/components/containers/settings/ConfigCreationForm.vue
@@ -86,7 +86,7 @@
           <p class="font-weight-regular body-1">
             Once you fetch the API response, you can convert the label into the defined one.
           </p>
-          <label-mapping v-model="templateConfig.label_mapping" />
+          <label-mapping v-model="labelMapping" />
         </v-stepper-content>
 
         <v-stepper-content step="3">
@@ -100,6 +100,18 @@
             outlined
             label="Sample Text"
           />
+          <v-alert
+            v-for="(error, index) in errors"
+            prominent
+            type="error"
+            :key="index"
+          >
+            <v-row align="center">
+              <v-col class="grow">
+                {{ error }}
+              </v-col>
+            </v-row>
+          </v-alert>
         </v-stepper-content>
       </v-card-text>
       <v-card-actions class="me-4">
@@ -163,13 +175,15 @@ export default Vue.extend({
 
   data() {
     return {
+      errors: [] as string[],
       isLoading: false,
       passTesting: false,
       sampleText: '',
       step: new StepCounter(1, 3),
       templateName: null,
       templateConfig: {},
-      templateNames: [] as string[]
+      templateNames: [] as string[],
+      labelMapping: []
     }
   },
 
@@ -188,6 +202,12 @@ export default Vue.extend({
         this.passTesting = false
       },
       deep: true
+    },
+    labelMapping: {
+      handler() {
+        this.passTesting = false
+      },
+      deep: true
     }
   },
 
@@ -217,7 +237,7 @@ export default Vue.extend({
         // @ts-ignore
         template: this.templateConfig.template,
         // @ts-ignore
-        labelMapping: this.templateConfig.label_mapping
+        labelMapping: this.labelMapping
       }
       return ConfigItem.parseFromUI(payload)
     },
@@ -229,6 +249,19 @@ export default Vue.extend({
         .then(value => {
           this.passTesting = value.valid
         })
+        .catch((error) => {
+          const data = error.response.data
+          this.errors = []
+          if ('non_field_errors' in data) {
+            this.errors = data['non_field_errors']
+          } else if ('template' in data) {
+            this.errors.push('The template need to be filled.')
+          } else if ('detail' in data) {
+            this.errors.push(data['detail'])
+          } else {
+            this.errors = data
+          }
+        })
         .finally(() => {
           this.isLoading = false
         })
diff --git a/frontend/components/containers/settings/LabelMapping.vue b/frontend/components/containers/settings/LabelMapping.vue
index 361a3be4..74b392ce 100644
--- a/frontend/components/containers/settings/LabelMapping.vue
+++ b/frontend/components/containers/settings/LabelMapping.vue
@@ -16,7 +16,7 @@
             v-bind="attrs"
             v-on="on"
           >
-            Add a mapping
+            Add
           </v-btn>
         </template>
         <v-card>