Amplify Auth: Device Tracking Issue & Solutions

Nov 10, 2025 by Admin 48 views

Amplify Authentication: Device Not Being Tracked - Troubleshooting and Solutions

Hey guys! If you're wrestling with device tracking issues in your AWS Amplify authentication setup, you're not alone. This guide dives deep into a specific problem: devices not being correctly recognized after the initial sign-in, even when MFA (Multi-Factor Authentication) is enabled and the device isn't set to be remembered. We'll explore the problem, the expected behavior, the steps to reproduce the issue, and potential solutions to ensure your users have a smooth and secure experience. Let's get started!

Understanding the Problem: Device Tracking in Amplify Auth

So, what's the deal? You've got Amplify Auth set up, MFA is working, and you expect your users to be prompted for 2FA when they log in from a new device or when they choose not to remember a device. Great. However, the documentation says that even when a device isn't remembered, it should still be tracked. The problem arises when, instead of recognizing the device, Amplify treats it as a completely new device with each login. This creates duplicate entries in the device list and generally throws off the expected user experience.

This behavior is counterintuitive. When a user logs in from the same browser or device, they should ideally be prompted for 2FA only when the device isn't remembered, and the device information should be consistent. The core issue is that Amplify is issuing a new device key, as identified during the SRP (Secure Remote Password) workflow, rather than recognizing the existing device. This can lead to a messy and confusing device list for your users.

The Impact of Incorrect Device Tracking

Why does this matter? Well, a couple of key reasons:

Poor User Experience: Imagine a user seeing multiple entries for the same device. It looks messy, and it’s confusing. Users rely on the ability to manage their devices and this inconsistency can be a real pain.
Inaccurate Device Lists: This makes it harder for users to manage their devices. It’s supposed to be a list of the devices they use, not a constantly-growing list of duplicates.
Security Concerns: Although not the primary issue here, managing devices correctly is crucial for security. Properly tracking devices helps you monitor potential misuse or unauthorized access. You want to make sure the right people are using the right devices, and consistent tracking is a part of that.

The Role of Device Keys and SRP

During the SRP workflow, a device_key is provided. This key should be used to identify a device across multiple logins. When this key isn’t passed correctly during subsequent authentication steps (e.g., when resolving the TOTP challenge), the device might be seen as new. The implication is that something is going wrong within the authentication flow after the initial sign-in.

Reproduction Steps: How to Recreate the Device Tracking Issue

Let’s get our hands dirty and figure out how to reproduce this issue. Here’s a detailed step-by-step guide to help you pinpoint the problem yourself.

Sign-in with MFA/TOTP Enabled: This is your starting point. Use the signIn() function in your code, providing the username and password.
```
const { isSignedIn, nextStep } = await signIn({
    username: <username>,
    password: <password>
});
```
Resolve the Challenge: After a successful sign-in, you’ll likely be prompted for a challenge, such as a TOTP (Time-Based One-Time Password) code. Use the confirmSignIn() function, providing the correct challenge response.
```
const { isSignedIn } = await confirmSignIn({
    challengeResponse: <code>
});
```
Fetch the Device List: Once the user is authenticated, fetch the list of devices associated with their account. The fetchDevices() function is typically used for this.
```
const devices = await fetchDevices()
```

Expected vs. Actual Behavior: The Discrepancy

Expected Outcome: When performing the above operations multiple times from the same device, you should see only one entry in the device list. Amplify should correctly identify the device and update any relevant information.

Actual Outcome: What you’re likely seeing is a new device being added to the list each time. Instead of updating the existing device record, Amplify is creating a new one, leading to duplicated entries.

Troubleshooting and Potential Solutions: Fixing Device Tracking in Amplify Auth

Now, let's explore some potential solutions and workarounds to address the device tracking problem. The goal is to ensure the device is correctly recognized after the initial login.

Verify Amplify Version and Configuration

Make sure you're using the latest versions of @aws-amplify/auth and aws-amplify. Old versions might have bugs that have since been fixed. Also, double-check your aws-exports.js file and any manual configuration you've done. Errors in configuration are often the cause of these types of issues.

Examine the Cognito User Pool Configuration

Device Tracking Settings: Review your Cognito User Pool settings. Ensure that device tracking is enabled and configured correctly. The settings might include options such as device remembering duration and the types of devices that are tracked.
MFA Settings: Carefully examine your MFA settings within Cognito. Make sure MFA is configured as expected and that it interacts correctly with device tracking. Misconfigurations here can sometimes disrupt device recognition.
SRP Workflow: During the SRP flow, the device key is provided. The key is vital for the authentication process, and it needs to be consistently managed. If not handled correctly, subsequent requests may not be properly linked to the initial device identification.

Investigate the `confirmSignIn` Function and `device_key`

As the original issue description pointed out, the device_key may not be correctly passed within the confirmSignIn function. Here’s what you can do:

Inspect the confirmSignIn Function: Review the implementation of confirmSignIn in your code. Make sure that the device_key is being correctly passed along during the challenge resolution. It's possible that this key is missing.
Manually Pass the device_key: As a test, try passing the device_key to the confirmSignIn function. If, by passing the device_key, Amplify stops treating the device as new, the issue likely lies in how this key is being handled during the authentication flow. This helps isolate the problem.
Update LastAuthenticatedDate: Even if you successfully pass the device_key, the LastAuthenticatedDate on the device might not be updated. This is a separate issue that needs to be addressed. Make sure that the authenticated date is appropriately updated in your code.

Logging and Debugging

Detailed Logging: Add extensive logging to your authentication flow, especially around the signIn, confirmSignIn, and fetchDevices calls. Log the device key at each stage, along with any error messages. This can offer clues as to where the process is failing.
Network Requests: Use your browser's developer tools to monitor the network requests. Check the requests and responses during the authentication process. You can see how the device key is being passed and whether the Cognito service is correctly recognizing the device.

Potential Code Modifications (Use with Caution)

Custom Authentication Flow: If the above steps don’t work, you might have to consider implementing a custom authentication flow. This gives you more control over the process, allowing you to explicitly handle the device_key and ensure that the device is correctly recognized.
Custom Challenge Resolvers: You could create custom challenge resolvers that correctly pass the device_key. However, this requires a deeper understanding of Amplify's internals. Be cautious and test thoroughly.

Community and Official Documentation

Amplify Documentation: Always consult the official Amplify documentation. They often provide troubleshooting guides and code samples that can help you with your specific issue.
GitHub Issues: Check the Amplify GitHub repository for open and closed issues related to device tracking. Other users might have encountered the same problem, and you can learn from their solutions. Don't hesitate to open a new issue yourself, providing detailed information about your problem.

Conclusion: Keeping Devices Tracked

Dealing with device tracking issues can be frustrating, but by systematically working through these steps, you should be able to identify and resolve the problem. The core takeaway is to ensure that the device_key is consistently handled throughout the authentication flow, especially when resolving challenges like TOTP. By doing so, you can ensure that Amplify recognizes the user's device and provides a seamless and user-friendly authentication experience.

Remember to test thoroughly after making any changes, and always stay up-to-date with the latest Amplify documentation and updates. Good luck, and happy coding!