Stop Nayax errors on your AI Smart Cooler or Vending Machine!  This guide targets the Nayax VPOS Touch and AI Smart Coolers. Learn the pre-authorization secrets you need to know to fix declines and unlock your profits.

AI Smart Coolers usually rely on a pre-authorization payment flow or incremental pre-authorization.  ReyVend offers both options but recommends incremental pre-authorization for increased sales and a better consumer experience.  The core difference between standard pre-authorization and incremental pre-authorization—the two payment flows used by AI Smart Coolers—is determined by how the customer's funds are secured and held.

Nayax Error Codes and Solutions for Smart Vending on MDB Protocol

 

The chart below details the key differences based on the initial hold amounts, customer bank statements, door unlock triggers, decline rates, and recommended use cases.

Smart Vending with Pre-Authorization Smart Vending with Incremental Authorization
Initial Hold Amount Fixed, High amount (e.g., $15 - $25). Set to cover the maximum amount someone is likely to purchase or steal. Low initial amount (e.g., $5 - $10). Set to cover a small to normal purchase.
Customer Statement This amount appears as a single pending charge or hold which appears right away on the customer's credit card. Multiple, increasing pending charges (e.g., $5, then $10, then $15) may appear.
The "Unlock" Trigger The pre-authorization amount must be approved (sufficient funds) and if so, the hold occurs and allows the smart cooler door to unlock. If this smaller amount is approved (sufficient funds), the hold occurs and allows the vending cooler to unlock.
Risk/Decline Rate Higher decline rate due to a higher initial amount that must be approved. Hence, someone that wants to just buy a Coke for $2.00 may not be approved if the pre-authorization amount is $20 and they don't have $20 in their account. Hence, a potential customer that has $15 in their bank account can't proceed with a $2.00 purchase if the pre-authorization amount is set to $20. Lower decline rate since the initial hold amount is smaller. Hence, people with low bank balances may have enough funds to trigger the unlock.
Best For High-value, high-risk items (e.g., electronics, large food orders). Simpler processing. High-volume, low-risk items (e.g., drinks, snacks). Best customer experience.


Why Incremental Authorization is Better for Smart Coolers:

Incremental authorization is the preferred method for AI Coolers. It ensures the customer has the initial funds to open the door, then allows the final charge to settle without immediately blocking the full high-risk amount on the user's card. This reduces customer calls complaining about "overcharges" on their pending statement.

Troubleshooting VPOS Touch Pre-Authorization Failures

When a customer taps their card and the door fails to unlock, the error is a Pre-Authorization failure. This is categorized into three main sources: Payment, Cooler, or Communication.

1. Payment Errors (Immediate Decline)

Symptom Cause Solution
Immediate Red Light / Decline Insufficient Funds for the Hold. The customer's bank declined the full Pre-Auth amount (e.g., $20), not the price of a single product. Operator Action (in Nayax Core/DCS): Lower the Pre-Authorization amount in the Payment Settings of the machine. The lower the hold, the fewer declines you'll see.
Stuck on "Authorizing..." High Network Latency or Weak Signal. The VPOS Touch cannot complete the handshake with the bank server fast enough.

1. Check RSSI (Signal Strength) in Technician Mode.


2. Move the external antenna to a higher position outside the cabinet.


3. Power cycle the machine to force a modem reset.
V01 / V02 after tap MDB Configuration Conflict. The VPOS is trying to interact with the cooler's controller (VMC) as a standard vending machine, confusing the process. Operator Action (in Nayax Core/DCS): For AI Coolers, the VPOS settings must be simple. Ensure MDB Flags are set to 'Flags Disabled' and the MDB Level is correctly set (usually Level 3 or a custom protocol for smart coolers).

2. Cooler Errors (Lock/Sensor Failure)

These errors occur after Nayax approves the charge but the door still won't open. The VPOS Touch often resets or shows a generic error.

Symptom Cause Solution
Yellow Light, Approved, No Unlock Click Failure to Execute Pulse. Nayax approved the payment and sent the digital signal (pulse), but the cooler's physical locking solenoid failed to receive or execute the command.

1. Check the physical MDB/Pulse cable connection from the VPOS Touch to the cooler's lock control board.


2. Physically inspect the door lock solenoid for debris or damage.
Door Unlocks, Transaction Stays "Open" Door Sensor Failure. The cooler's internal sensor didn't register the door being closed after the transaction.

1. Check the magnetic reed switch or latch mechanism on the door.


2. If the cooler uses a specific SDK/API, ensure the Nayax "Door Open Functionality" setting in DCS is correct (often set to 'As Cancel' or Door Open as Cancel).

This guide is focused exclusively on using the Nayax VPOS Touch reader with AI Smart Coolers (grab-and-go fridges), detailing the critical pre-authorization logic and offering targeted troubleshooting.

The primary function of the Nayax VPOS Touch on an AI Smart Cooler is to act as the secure gatekeeper that uses an authorization hold to trigger the door unlock.

 

🔒 Pre-Authorization vs. Incremental Authorization in AI Coolers

 

The core difference between these two payment flows affects the customer experience, the likelihood of a decline, and the risk management for the operator.

Feature Standard Pre-Authorization (Standard P.A.) Incremental Authorization (I.A.)
Initial Hold Amount Fixed, High amount (e.g., $15 - $25). Set to cover the maximum likely purchase or theft risk. Low initial amount (e.g., $5 - $10). Set to cover a small base purchase.
Customer Statement Single, high pending charge (e.g., $20) appears immediately. Multiple, increasing pending charges (e.g., $5, then $10, then $15) may appear.
The "Unlock" Trigger High hold must be approved $\rightarrow$ Door unlocks. Low hold must be approved $\rightarrow$ Door unlocks.
Risk/Decline Rate Higher decline rate. A customer with $18 in the bank is declined for a $20 hold, even if they only buy a $5 item. Lower decline rate. More cards pass the initial check.
Best For High-value, high-risk items (e.g., electronics, large food orders). Simpler processing. High-volume, low-risk items (e.g., drinks, snacks). Best customer experience.

 

Why Incremental Authorization is Better for Smart Coolers:

Incremental authorization is the preferred method for AI Coolers. It ensures the customer has the initial funds to open the door, then allows the final charge to settle without immediately blocking the full high-risk amount on the user's card. This reduces customer calls complaining about "overcharges" on their pending statement.

 

Troubleshooting VPOS Touch Pre-Authorization Failures:

When a customer taps their card and the door fails to unlock, the error is a Pre-Authorization failure. This is categorized into three main sources: Payment, Cooler, or Communication.

1. Payment Errors (Immediate Decline)

Symptom Cause Solution
Immediate Red Light / Decline Insufficient Funds for the Hold. The customer's bank declined the full Pre-Auth amount (e.g., $20), not the price of a single product. Operator Action (in Nayax Core/DCS): Lower the Pre-Authorization amount in the Payment Settings of the machine. The lower the hold, the fewer declines you'll see.
Stuck on "Authorizing..." High Network Latency or Weak Signal. The VPOS Touch cannot complete the handshake with the bank server fast enough.

1. Check RSSI (Signal Strength) in Technician Mode.


2. Move the external antenna to a higher position outside the cabinet.


3. Power cycle the machine to force a modem reset.
V01 / V02 after tap MDB Configuration Conflict. The VPOS is trying to interact with the cooler's controller (VMC) as a standard vending machine, confusing the process. Operator Action (in Nayax Core/DCS): For AI Coolers, the VPOS settings must be simple. Ensure MDB Flags are set to 'Flags Disabled' and the MDB Level is correctly set (usually Level 3 or a custom protocol for smart coolers).

 

2. Cooler Errors (Lock/Sensor Failure)

These errors occur after Nayax approves the charge but the door still won't open. The VPOS Touch often resets or shows a generic error.

Symptom Cause Solution
Yellow Light, Approved, No Unlock Click Failure to Execute Pulse. Nayax approved the payment and sent the digital signal (pulse), but the cooler's physical locking solenoid failed to receive or execute the command.

1. Check the physical MDB/Pulse cable connection from the VPOS Touch to the cooler's lock control board.


2. Physically inspect the door lock solenoid for debris or damage.
Door Unlocks, Transaction Stays "Open" Door Sensor Failure. The cooler's internal sensor didn't register the door being closed after the transaction.

1. Check the magnetic reed switch or latch mechanism on the door.


2. If the cooler uses a specific SDK/API, ensure the Nayax "Door Open Functionality" setting in DCS is correct (often set to 'As Cancel' or Door Open as Cancel).

 

3. Settlement Errors (Customer Complaint)

Symptom Cause Solution
"I was charged $20 but only bought a $5 item!" Hold not released immediately. The customer sees the full Standard Pre-Auth hold on their banking app, and the final settlement hasn't completed yet.

1. Explain the process to the customer: "That is a temporary security hold that will drop in 24-48 hours. You only pay for what you took."


2. Operator Action: Switch to Incremental Authorization in Nayax Core to prevent this shock.
Final charge is wrong (over/under charged) Cooler Calibration/Sensor Error. The cooler's internal software (vision system or weight sensors) incorrectly calculated the contents taken. Nayax is not at fault. Calibrate or reset the cooler's inventory system. Check for items falling into the "blind zone" (e.g., under the shelves).


Configuration Deep Dive: Essential Settings

For a reliable AI Smart Cooler operation with Nayax VPOS Touch, confirm these settings in the Nayax Core management system:

Setting Group Field Recommended Value (AI Cooler) Why?
Card Reader Transaction Start Method Mag, Contact plus Contactless Ensures all tap/swipe methods are accepted.
MDB MDB Flags Flags Disabled Prevents MDB commands from interfering with the cooler's specific access protocol.
Payment Support Incremental Authorization Checked/Enabled Recommended for better customer experience (low initial hold).
Payment Initial/Default Credit Amount $3.00 - $5.00 Sets the low starting hold for Incremental Authorization.
Payment Max Authorization Amount $15.00 - $25.00 Sets the maximum limit for a single session to mitigate theft risk.
Device Features Door Open Functionality As Cancel (or similar) Crucial: Tells Nayax to cancel the charge if the door is opened and closed without the cooler sending a final vend signal.


✅ Nayax VPOS Touch Troubleshooting Checklist For AI Smart Coolers

 

1. Physical Installation & Power

Checkpoint Task Why it Matters
Power Cycle Unplug the main machine power. Do not install the reader while the machine is live. Prevents power surges or electrical damage to the reader and the VMC.
MDB Connection Ensure the MDB Y-cable is firmly connected to the Nayax reader, the VMC (Cooler Controller), and the Coin/Bill Acceptor (if present). Prevents V00 errors. A loose connection is the #1 cause of communication failure.
Antenna Placement Mount the antenna outside the metal cabinet (usually on top). Keep the antenna cable away from power lines and motors. Prevents M02/M03 errors. Metal cabinets block signal (Faraday Cage effect). Good placement ensures strong RSSI (signal strength).
Cooler Pulse Wire If the cooler uses a dedicated Pulse/Relay wire for the door lock (instead of MDB), ensure it is connected to the designated port on the VPOS Touch harness. Ensures the Nayax can physically send the UNLOCK command after successful pre-authorization.

 

2. Initial Boot & Signal Check

Checkpoint Task Target Status Why it Matters
Boot Sequence Plug the machine back in. Wait for the VPOS Touch to display "Present Card". Status: M00 (Initializing) $\rightarrow$ M02/M03 (Signal Search) $\rightarrow$ "Present Card" Confirms the modem is attempting to connect and initialize correctly.
Signal Strength (RSSI) Enter Technician Mode (press and hold the yellow button for 5 seconds) and check the RSSI (Signal) reading. Target: Stronger than -90 dBm. (e.g., -60 dBm is excellent; -100 dBm is unusable). Poor signal leads to slow authorization and dropped settlements (M05 errors).
Test Transaction Use an employee card to perform a $1.00 test tap. Do not open the door. Result: Tap should succeed, and the reader should show the Pre-Auth Hold. Confirms the device can successfully connect to the Nayax server and the banking network.

 

3. Nayax Core (DCS) Settings Check

Checkpoint Task Correct Setting (AI Cooler) Why it Matters
Pre-Authorization Amount Confirm the maximum hold placed on the customer's card. Set Low ($10.00 recommended) OR Enable Incremental Auth. Prevents high decline rates and customer complaints about "ghost charges."
MDB Flags Check that the device is configured to handle the cooler's unique logic, not standard vending. 'Flags Disabled' or the specific vendor-required flag. Prevents V01 errors by avoiding protocol confusion with the smart cooler VMC.
Time Zone Verify that the machine's time zone is correctly set. Accurate local time. Ensures accurate reconciliation and prevents authorization errors related to timestamping.
Machine Status Confirm the machine is marked as 'Active' in Nayax Core. Active / Ready. Prevents server-side declines even if the physical reader is working perfectly.


Nayax Driver/Technician Quick Fix Sheet

Error/Check Meaning Action / Solution
V-CODES (Machine Connection) Reader cannot talk to the Vending Machine (Cooler).
V00 (Comm. Error) MDB cable is loose or disconnected.

1. Power Cycle: Unplug machine for 60 seconds.


2. Check the thick black MDB cable. Is it secure?
V01 (Config Error) MDB settings are wrong for a smart cooler (Admin issue). Call Office/Admin to check MDB Level in DCS. Do not swap the reader.
V02 (Cashless Off) The Vending Machine Controller disabled card payments. Check Cooler's internal menu to ensure "Cashless" is set to ON.
M-CODES (Network/Modem) Reader cannot talk to the Internet/Nayax server.
M00 (Initializing) Modem is trying to start up. WAIT 5 minutes. If stuck, perform a power cycle.
M01 (SIM Error) SIM card is missing or misaligned.

1. Power OFF.


2. Remove SIM, wipe chip, and re-insert firmly. Power ON.
M02 / M03 (No Signal) Poor cellular connection.

1. Move antenna to a higher position (outside the metal cabinet).


2. Check antenna cable for damage or kinks.
AI COOLER CHECKS Door/Lock related issues.
Red Light / Decline Customer's funds failed the initial Pre-Auth hold. The customer needs more money in their account to cover the hold (not the product cost).
Door Won't Lock The magnetic sensor is not registering the door as closed. Check for debris in the door latch/magnet. Push the door firmly closed.
Beeping Loudly Session Timeout (door was open too long). Close the door immediately and wait for the "Thank You" message.