diff --git a/src/handlers/db.ts b/src/handlers/db.ts
index db79ffb..72a02b3 100644
--- a/src/handlers/db.ts
+++ b/src/handlers/db.ts
@@ -58,3 +58,10 @@ export function handlePrismaError(errorObj: any, res: Response, source: string)
 export default prisma;
 
 //FIXME: https://www.prisma.io/docs/orm/prisma-client/special-fields-and-types/null-and-undefined
+
+
+// // Simulate a Prisma error for testing purposes
+// throw new Prisma.PrismaClientKnownRequestError(
+// 	'Simulated Prisma error for testing',
+// 	{ code: 'P2000', clientVersion: 'unknown' } // Example error parameters
+// );
diff --git a/src/routes/api/v1/transaction/transaction.ts b/src/routes/api/v1/transaction/transaction.ts
index 4405014..e84b90d 100644
--- a/src/routes/api/v1/transaction/transaction.ts
+++ b/src/routes/api/v1/transaction/transaction.ts
@@ -5,6 +5,13 @@ import { parseDynamicSortBy } from '../../../../helpers/prisma_helpers.js';
 import { schema_get, schema_post, schema_patch, schema_del } from './transaction_schema.js';
 import { Prisma } from '@prisma/client';
 
+class AbortError extends Error {
+	constructor(public http_status: number, public status: string, public errorcode: string, public message: string, public details?: any) {
+		super(message);
+		this.name = 'AbortError';
+	}
+}
+
 // MARK: GET transaction
 async function get(req: Request, res: Response) {
 	const { error, value } = schema_get.validate(req.query);
@@ -94,38 +101,81 @@ async function post(req: Request, res: Response) {
 		log.api?.debug('POST transaction Success:', req.body, value);
 
 		const products: Array<number> = value.products;
-		let total = new Prisma.Decimal(0);
+		const outOfStockProducts: { id: number; name: string }[] = [];
+		const notFoundProducts: { id: number; name: string }[] = [];
 		const salesData: { productId: number; price: number }[] = [];
+		let total = new Prisma.Decimal(0);
 
-		try {
-			// Start Prisma transaction
-			await db.$transaction(async (prisma) => {
+		// Start Prisma transaction
+		await db
+			.$transaction(async (prisma) => {
+				// Iterate over all products for this transaction(not prisma)
 				for (let i = 0; i < products.length; i++) {
-					log.api?.debug('Product:', products[i]);
+					log.api?.debug('Product:', i + 1, 'of', products.length, '(Loop)');
+
+					// Get product (price, stock, name)
 					const product = await prisma.products.findUnique({
 						where: { id: products[i] },
-						select: { price: true }
+						select: { price: true, stock: true, name: true }
 					});
 
+					// Check if product exists
 					if (product) {
-						log.api?.debug('Price:', product.price, Number(product.price));
-						//total += Number(product.price);
-						total = total.add(product.price);
+						log.api?.debug('Price:', product.price, '[Name:' + product.name + ']', '[ID:' + products[i] + ']');
 
-						salesData.push({
-							productId: products[i],
-							price: Number(product.price)
-						});
+						if (product.stock > 0) {
+							// Add price of current product to total
+							total = total.add(product.price);
+
+							// Add product to salesData -> Later generate sales entry for each product
+							salesData.push({
+								productId: products[i],
+								price: Number(product.price)
+							});
+
+							// Reduce stock by 1
+							await prisma.products.update({
+								where: { id: products[i] },
+								data: { stock: { decrement: 1 } }
+							});
+						} else {
+							// Product is out of stock
+							outOfStockProducts.push({ id: products[i], name: product.name });
+						}
 					} else {
-						log.api?.debug('Product not found:', products[i]);
+						// Product not found
+						notFoundProducts.push({ id: products[i], name: 'unknown' });
 					}
 				}
 
 				log.api?.debug('Total:', total.toFixed(2));
 
-				// TODO: Check if user exists
+				// Abort the Prisma transaction if there are not existing products
+				if (notFoundProducts.length > 0) {
+					log.api?.debug('Aborting. missing products:', notFoundProducts);
 
-				// Create transaction with sales
+					throw new AbortError(
+						400, // http_status
+						'ERROR', // status
+						'NOT_FOUND', // errorcode
+						'Some of the products included in the transaction do not exist, therefore the transaction has not been processed.', // message
+						notFoundProducts // details
+					);
+				}
+
+				// Abort the Prisma transaction if there are products with insufficient stock
+				if (outOfStockProducts.length > 0) {
+					log.api?.debug('Aborting. out of stock products:', outOfStockProducts);
+					throw new AbortError(
+						400, // http_status
+						'ERROR', // status
+						'OUT_OF_STOCK', // errorcode
+						'Some of the products included in the transaction are out of stock, therefore the transaction has not been processed.', // message
+						outOfStockProducts // details
+					);
+				}
+
+				// Create transaction with salesData
 				const transaction = await prisma.transactions.create({
 					data: {
 						userId: value.user_id,
@@ -140,11 +190,21 @@ async function post(req: Request, res: Response) {
 					}
 				});
 
+				// Everything went well
 				res.status(201).json({ status: 'CREATED', message: 'Successfully created transaction', id: transaction.id });
+			})
+			.catch((err) => {
+				if (err instanceof AbortError) {
+					res.status(err.http_status).json({
+						status: err.status,
+						errorcode: err.errorcode,
+						message: err.message,
+						details: err.details
+					});
+				} else {
+					handlePrismaError(err, res, 'POST transaction');
+				}
 			});
-		} catch (err) {
-			handlePrismaError(err, res, 'POST transaction');
-		}
 	}
 }