diff --git a/packages/n8n-node/nodes/Probo/actions/accessReview/addSource.operation.ts b/packages/n8n-node/nodes/Probo/actions/accessReview/addSource.operation.ts
new file mode 100644
index 000000000..1056921e5
--- /dev/null
+++ b/packages/n8n-node/nodes/Probo/actions/accessReview/addSource.operation.ts
@@ -0,0 +1,87 @@
+// Copyright (c) 2025-2026 Probo Inc <hello@probo.com>.
+//
+// Permission is hereby granted, free of charge, to any person obtaining a copy
+// of this software and associated documentation files (the "Software"), to deal
+// in the Software without restriction, including without limitation the rights
+// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+// copies of the Software, and to permit persons to whom the Software is
+// furnished to do so, subject to the following conditions:
+//
+// The above copyright notice and this permission notice shall be included in
+// all copies or substantial portions of the Software.
+//
+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+// SOFTWARE.
+
+import type { INodeProperties, IExecuteFunctions, INodeExecutionData } from 'n8n-workflow';
+import { proboApiRequest } from '../../GenericFunctions';
+
+export const description: INodeProperties[] = [
+	{
+		displayName: 'Access Review Campaign ID',
+		name: 'accessReviewCampaignId',
+		type: 'string',
+		displayOptions: {
+			show: {
+				resource: ['accessReview'],
+				operation: ['addSource'],
+			},
+		},
+		default: '',
+		description: 'The ID of the access review campaign',
+		required: true,
+	},
+	{
+		displayName: 'Access Review Source ID',
+		name: 'accessReviewSourceId',
+		type: 'string',
+		displayOptions: {
+			show: {
+				resource: ['accessReview'],
+				operation: ['addSource'],
+			},
+		},
+		default: '',
+		description: 'The ID of the access review source to add to the campaign',
+		required: true,
+	},
+];
+
+export async function execute(
+	this: IExecuteFunctions,
+	itemIndex: number,
+): Promise<INodeExecutionData> {
+	const accessReviewCampaignId = this.getNodeParameter('accessReviewCampaignId', itemIndex) as string;
+	const accessReviewSourceId = this.getNodeParameter('accessReviewSourceId', itemIndex) as string;
+
+	const query = `
+		mutation AddAccessReviewCampaignSource($input: AddAccessReviewCampaignSourceInput!) {
+			addAccessReviewCampaignSource(input: $input) {
+				accessReviewCampaign {
+					id
+					name
+					description
+					status
+					startedAt
+					completedAt
+					createdAt
+					updatedAt
+				}
+			}
+		}
+	`;
+
+	const responseData = await proboApiRequest.call(this, query, {
+		input: { accessReviewCampaignId, accessReviewSourceId },
+	});
+
+	return {
+		json: responseData,
+		pairedItem: { item: itemIndex },
+	};
+}
diff --git a/packages/n8n-node/nodes/Probo/actions/accessReview/index.ts b/packages/n8n-node/nodes/Probo/actions/accessReview/index.ts
index 18eb48ba5..4a71bd6e5 100644
--- a/packages/n8n-node/nodes/Probo/actions/accessReview/index.ts
+++ b/packages/n8n-node/nodes/Probo/actions/accessReview/index.ts
@@ -19,6 +19,7 @@
 // SOFTWARE.
 
 import type { INodeProperties } from 'n8n-workflow';
+import * as addSourceOp from './addSource.operation';
 import * as createOp from './create.operation';
 import * as deleteOp from './delete.operation';
 import * as getOp from './get.operation';
@@ -40,6 +41,12 @@ export const description: INodeProperties[] = [
 			},
 		},
 		options: [
+			{
+				name: 'Add Source',
+				value: 'addSource',
+				description: 'Add a scope source to an access review campaign',
+				action: 'Add a scope source to an access review campaign',
+			},
 			{
 				name: 'Cancel',
 				value: 'cancel',
@@ -91,6 +98,7 @@ export const description: INodeProperties[] = [
 		],
 		default: 'create',
 	},
+	...addSourceOp.description,
 	...createOp.description,
 	...deleteOp.description,
 	...getOp.description,
@@ -102,6 +110,7 @@ export const description: INodeProperties[] = [
 ];
 
 export {
+	addSourceOp as addSource,
 	createOp as create,
 	deleteOp as delete,
 	getOp as get,
diff --git a/pkg/server/api/console/v1/access_review_campaign_resolvers.go b/pkg/server/api/console/v1/access_review_campaign_resolvers.go
index 9f1411bce..3edce2568 100644
--- a/pkg/server/api/console/v1/access_review_campaign_resolvers.go
+++ b/pkg/server/api/console/v1/access_review_campaign_resolvers.go
@@ -9,6 +9,7 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"strings"
 
 	"github.com/vikstrous/dataloadgen"
 	"go.gearno.de/kit/log"
@@ -796,6 +797,10 @@ func (r *mutationResolver) StartAccessReviewCampaign(ctx context.Context, input
 
 	campaign, err := r.accessReview.StartCampaign(ctx, scope, input.AccessReviewCampaignID)
 	if err != nil {
+		if strings.HasPrefix(err.Error(), "cannot start campaign:") {
+			return nil, gqlutils.Invalid(ctx, err)
+		}
+
 		r.logger.ErrorCtx(ctx, "cannot start access review campaign", log.Error(err))
 
 		return nil, gqlutils.Internal(ctx)