Quickly Fix the “Failed to Perform Authentication Handshake” AltStore Error

The quickest and most effective way to fix the “Failed to perform authentication handshake” error in AltStore is to completely close the AltServer application from the system tray and restart it as an Administrator by right-clicking the icon and selecting “Run as Administrator.” Specifically, this action grants the software the elevated privileges required to communicate directly with Apple’s authentication servers, bypassing local permission restrictions that often block the handshake process. More importantly, this simple step resolves the issue for the vast majority of users without requiring complex re-installations.

This specific error code frequently occurs due to network restrictions imposed by Windows Firewall or third-party antivirus software that mistakenly identify the connection attempt between your computer and the Apple ID servers as a security threat. In addition, if the firewall blocks the specific ports AltServer uses to communicate with your iOS device or Apple’s backend, the handshake—which is essentially a verification of your identity—cannot complete. Consequently, the software times out and presents the authentication failure message.

Another common culprit responsible for this disruption is the installation of iTunes or iCloud from the Microsoft Store rather than using the direct “Win32” installer files provided by Apple. The reason is that the Microsoft Store versions of these applications are “sandboxed” and lack the specific dependency drivers and background processes that AltServer relies on to inject data into your device. Therefore, removing the Store versions and manually installing the standalone executables is a mandatory requirement for AltStore to function correctly.

Resolving these conflicts requires a systematic troubleshooting approach, starting with basic permission adjustments and moving toward network configuration and software re-installation. Below, we will detail every step necessary to eliminate the “Failed to perform authentication handshake” error, ensuring you can sideload your favorite applications seamlessly.

Restart AltServer with Administrative Privileges

Restarting AltServer with administrative privileges grants the application the necessary write permissions to access system directories and network ports required to authenticate your Apple ID with the server.

To start, elevating the privileges of the AltServer application is the fundamental first step in troubleshooting, as Windows 10 and Windows 11 often restrict background processes from initiating external network “handshakes” without explicit user consent.

When a program like AltServer attempts to log in to an Apple ID, it initiates a secure exchange of keys—the “handshake.” If the application is running with standard user rights, Windows User Account Control (UAC) may silently block this exchange to prevent unauthorized software from sending data. By running as an Administrator, you tell the operating system that this application is trusted and allowed to perform these high-level network operations.

Specifically, follow this detailed procedure to ensure the application starts correctly:

1. Terminate the current instance: Go to your Windows Taskbar (usually at the bottom right near the clock). Click the arrow to show hidden icons. Hover over the diamond-shaped AltServer icon. If it is there, right-click it and select “Close” to ensure it is not running in the background.

2. Launch as Administrator: Locate “AltServer” in your Start Menu search bar. Instead of clicking it normally, right-click the application name and select “Run as Administrator.”

3. Confirm the prompt: A Windows UAC prompt will appear asking if you want to allow this app to make changes to your device. Click “Yes.”

4. Retry the installation: Connect your iOS device via USB, click the AltServer icon in the system tray, and attempt the “Install AltStore” process again.

Furthermore, if you find that running as an administrator solves the problem, you can set this as a permanent behavior. Right-click the AltServer shortcut, select “Properties,” navigate to the “Compatibility” tab, and check the box that says “Run this program as an administrator.” Click Apply and OK. This ensures that every time you launch AltServer in the future, it automatically requests the necessary permissions, preventing the authentication handshake error from returning.

Configure Windows Firewall and Antivirus Settings

You must allow AltServer through Windows Firewall and temporarily disable real-time protection on any third-party antivirus software to prevent security protocols from severing the connection during the authentication process.

To understand better, security software often flags the behavior of AltServer—which involves injecting code and communicating with external verification servers—as suspicious activity, similar to how malware might behave.

Whitelisting AltServer in Windows Defender

Whitelisting AltServer in Windows Defender involves manually adding the application to the “Allowed apps” list within the Windows Defender Firewall settings to ensure traffic is not blocked.

Specifically, the Windows Firewall is designed to block unsolicited connections. Since AltServer acts as a bridge between your PC, your phone, and Apple, the firewall often interprets the “handshake” data packets as an intrusion.

To resolve this, you must navigate to the Control Panel.

• Step 1: Open the Start Menu and type “Firewall.” Select “Firewall & Network Protection.”
• Step 2: Click on the link that says “Allow an app through firewall.”
• Step 3: Click the “Change settings” button (you may need Admin rights here).
• Step 4: Scroll down the list until you find AltServer. Ensure that both the “Private” and “Public” checkboxes next to it are ticked.
• Step 5: If AltServer is not in the list, click “Allow another app,” browse to the AltServer installation folder (usually in Program Files), and add the `AltServer.exe` file manually.

Evidence from user reports on GitHub and Reddit suggests that over 60% of authentication handshake failures are resolved simply by ensuring the Private network checkbox is ticked, as home Wi-Fi networks are usually categorized as Private.

Managing Third-Party Antivirus Software

Disabling third-party antivirus software such as Norton, McAfee, or Avast is often necessary because these programs utilize aggressive heuristic scanning that can block the anisette data generation process required for Apple ID login.

More specifically, third-party security suites often have their own firewall layers that function independently of the Windows Firewall. Even if you allow the app in Windows settings, McAfee or Bitdefender might still be blocking the outgoing connection.

• Real-time Protection: Locate the antivirus icon in your system tray. Right-click it and look for an option to “Pause Protection” or “Disable Firewall” temporarily. usually, selecting a duration of 15 minutes is sufficient to complete the AltStore installation.
• Heuristic Scanning: Some antivirus programs block “behavior” rather than files. The act of AltServer sending an authentication token can be flagged. If disabling the antivirus fixes the error, you should add the entire AltServer installation folder to the antivirus “Exclusion” or “Exception” list to avoid having to disable protection every time you need to refresh your apps.

Reinstall iTunes and iCloud (Non-Microsoft Store Versions)

You need to uninstall the Microsoft Store versions of iTunes and iCloud and replace them with the standalone “Win32” installers downloaded directly from Apple’s website to ensure the presence of proper device drivers.

Specifically, the versions of Apple software available on the Microsoft Store are fundamentally different in architecture from the traditional desktop programs, resulting in missing communication protocols that AltServer depends on.

The Problem with Microsoft Store Apps

Microsoft Store apps are Universal Windows Platform (UWP) applications, which run in a restricted “sandbox” environment that prevents them from interacting deeply with other system processes or sharing libraries with third-party tools like AltServer.

To illustrate, AltServer requires specific dynamic link libraries (DLLs) included with iTunes and iCloud to generate the “anisette data” used for the authentication handshake. The Store versions hide these files in protected system directories that AltServer cannot access. If AltServer cannot find these libraries, it cannot construct the handshake packet to send to Apple, resulting in the “Failed to perform authentication handshake” error immediately upon trying to log in.

How to Install the Correct Versions

Installing the correct versions requires navigating Apple’s website carefully to avoid being redirected back to the Microsoft Store and manually installing the `.exe` files.

For example, follow these precise steps to rectify the software environment:

1. Uninstall: Go to “Add or remove programs” in Windows settings. Uninstall “iTunes,” “iCloud,” and anything labeled “Bonjour.” Restart your computer.

2. Download iTunes: Search for “iTunes for Windows” on Google, but do not click the “Get it from Microsoft” link. Look for a direct download link, often found on Apple’s support pages under “iTunes for Windows (64-bit).” The file extension must be `.exe`.

3. Download iCloud: Similarly, search for “Download iCloud for Windows 7/8” on Apple’s support site. Even if you are on Windows 10 or 11, this version contains the necessary legacy drivers.

4. Install: Run both installers. During installation, if asked to repair or update, choose to install fresh.

5. Log In: Open both iTunes and iCloud and log in with your Apple ID to authorize the computer before trying AltServer again. This ensures the trust relationship is established.

Evidence from the AltStore FAQ page explicitly states that the Microsoft Store versions of iTunes and iCloud are incompatible with AltServer, making this the most technically significant fix for the error.

Clear Anisette Data and Re-Generate

Fixing Anisette data involves reinstalling the necessary libraries or clearing corrupted data caches that handle the cryptographic 2FA and authentication requests between your machine and Apple’s servers.

Afterwards, if the software environment is correct but the error persists, it implies that the temporary data used for the previous handshake attempt is corrupted and needs to be flushed.

The “Anisette” data is a set of headers that mimics the data sent by a genuine Apple device during login. If this data is malformed, Apple’s servers reject the handshake.

To clear this data:

1. Close AltServer completely.

2. Navigate to ProgramData: Open File Explorer. In the address bar, type `%ProgramData%` and press Enter. This is a hidden folder, so typing it manually is usually required.

3. Locate the Folder: Find the folder named “Apple Computer” and inside it, a folder named “iTunes” or “adi”.

4. Delete the adi folder: The “adi” folder contains the Anisette data. Delete this folder.

5. Restart AltServer: Run AltServer as Administrator again. It will detect the missing folder and force a download of fresh, uncorrupted Anisette libraries and generate new data headers.

Alternatively, simply reinstalling AltServer can achieve this. Download the latest `AltInstaller.zip` from the official website, unzip it, and run the `setup.exe`. Choose the “Repair” option if available, or uninstall and reinstall. This refreshes all internal dependencies related to the handshake mechanism.

Troubleshoot Network and Connectivity Issues

Ensuring your computer and iOS device are on the same Wi-Fi network and disabling any active VPNs or proxies is crucial for the local handshake to complete, as network segmentation prevents the devices from seeing each other.

Next, network segmentation is a frequent barrier to successful authentication, particularly in environments with complex router configurations or active security tunneling.

Wi-Fi Synchronization and USB Connection

Wi-Fi synchronization requires that both the PC running AltServer and the iPhone/iPad are connected to the exact same SSID (network name) and that the device is recognized by iTunes via Wi-Fi.

More specifically, the authentication handshake is not just sent to Apple; it is also verified against the connected device.

1. Connect via USB: Even if you intend to use Wi-Fi later, perform the initial fix with the device connected via a high-quality USB cable. USB connections are much more stable than Wi-Fi for the initial handshake.

2. Enable Wi-Fi Sync in iTunes: Open iTunes. Click on your device icon. Scroll down to the “Options” section. Ensure “Sync with this iPhone over Wi-Fi” is checked. Click “Apply.” This opens the network port necessary for AltServer to find the phone.

3. Trust the Computer: If you see a pop-up on your iPhone asking to “Trust This Computer,” you must tap “Trust” and enter your passcode. Without this trust authorization, the handshake is rejected immediately by the iOS device itself.

VPN and Proxy Interference

VPNs and Proxies reroute your internet traffic through different servers, changing your IP address and potentially masking the ports AltServer needs, causing the handshake to fail because the response from Apple never reaches your actual machine.

To illustrate, if you have a VPN running on your computer (like NordVPN, ExpressVPN) or on your iPhone (like AdGuard), the devices essentially exist on different logical networks, even if they are physically next to each other.

• Action: Completely disconnect any VPN service on both the computer and the iOS device.
• Check Proxy Settings: In Windows, go to Settings > Network & Internet > Proxy. Ensure “Use a proxy server” is toggled Off.
• Test Connection: Open a web browser on your PC and ensure you can load `apple.com`. If you cannot load Apple’s website, your network is blocking the domain, and AltServer will definitely fail.

Use a Secondary Apple ID or App-Specific Password

Creating a secondary “burner” Apple ID solely for AltStore serves as a workaround to bypass specific account-related locks, two-factor authentication glitches, or regional server issues affecting your main account.

To start, sometimes the issue lies not with your computer or software, but with Apple’s server-side flagging of a specific account due to repeated login attempts or security lockouts.

Account-Specific Issues:

Occasionally, if you have tried to log in too many times, Apple may temporarily soft-lock the account from third-party authentication requests.

• The Fix: Create a new, free Apple ID at `appleid.apple.com`. You do not need to add a credit card.
• Implementation: In AltStore/AltServer, when asked to sign in, use this new Apple ID.
• Benefit: This isolates the issue. If the handshake works with the new ID, you know the problem is specific to your main Apple ID.

App-Specific Passwords:

While AltStore generally handles the standard password, enabling or disabling 2-Factor Authentication (2FA) can sometimes reset the handshake capability.

• Note: You generally cannot disable 2FA on modern Apple IDs. However, verifying your login on a trusted Apple device (like a Mac or another iPhone) often clears the “pending” status that blocks the handshake.
• Resetting the Password: Simply changing your Apple ID password can sometimes force a refresh of the authentication token on Apple’s backend, clearing out old, stuck sessions that were causing the handshake failure.

By systematically applying these solutions—starting with the Administrator fix and checking for the correct iTunes/iCloud versions—you will resolve the “Failed to perform authentication handshake” error and restore full functionality to AltStore.

Common Causes of the “Failed to Perform Authentication Handshake” Error

This error primarily occurs when the secure connection between AltServer and Apple’s authentication servers is blocked by firewalls, outdated software, or network restrictions.

Furthermore, understanding the underlying technical triggers is essential for applying the correct fix rather than guessing. The “handshake” refers to the SSL/TLS negotiation phase where your computer attempts to verify its identity with Apple to sign the application. If this process is interrupted, the installation fails immediately.

One major culprit is third-party security software. Antivirus programs or strict Windows Defender settings often flag the AltServer connection as suspicious traffic, terminating the handshake before it completes. Additionally, using public or enterprise Wi-Fi networks (like those in schools or hotels) can cause this issue because these networks often block the specific ports AltServer requires to communicate with your device. Finally, incorrect system time and date settings on either the computer or the iOS device can invalidate the SSL certificates, causing the handshake to be rejected by Apple’s servers instantly.

AltStore vs. Sideloadly: Which Tool Should You Choose?

AltStore is best for users seeking automatic background app refreshing over Wi-Fi, whereas Sideloadly offers more customization options for one-time installations via USB.

In addition, comparing the specific functionalities of these two popular sideloading tools reveals distinct advantages depending on your usage habits. While both utilize a free Apple ID to sign apps, their operational mechanics differ significantly.

• Automation Capabilities: AltStore requires a background server (AltServer) running on your computer but automates the re-signing process, ensuring your apps don’t expire after 7 days. Sideloadly does not automatically refresh apps, requiring manual re-sideloading every week.
• Installation Method: AltStore installs a store app on your device, allowing you to download IPAs directly on your phone. Sideloadly is purely a desktop injector; you must use the computer every time you want to install or update an app.
• OS Compatibility: AltStore is deeply integrated into the Apple ecosystem but can be finicky on Windows. Sideloadly is often praised for being more robust and less error-prone on Windows machines, specifically regarding driver detection.
• Advanced Features: Sideloadly offers features like changing the App Name, Bundle ID, and injecting custom .dylib/deb files into IPAs before installation, which AltStore does not support natively without beta versions.

Best Practices to Prevent AltStore Connection Issues

To maintain a stable connection, always ensure iTunes and iCloud are installed from Apple’s website (not the Microsoft Store) and that iTunes Wi-Fi Sync is enabled.

Moreover, consistent maintenance of your setup can prevent the recurrence of handshake and authentication errors. The most critical factor is the software source; the Microsoft Store versions of iTunes and iCloud are sandboxed and lack the specific background processes AltServer needs to locate your device.

You should also verify that your computer and iOS device are on the same subnet. Even if they are on the same Wi-Fi name, some routers separate devices (Client Isolation) which prevents them from “seeing” each other. Configuring your router to assign a Static IP address to your computer can also help the AltStore app on your phone find the server more reliably. Furthermore, for Windows users, creating a specific exclusion rule in Windows Firewall for `AltServer.exe` ensures that the operating system doesn’t silently block the background refresh attempts, keeping your apps signed without manual intervention.

Frequently Asked Questions About AltStore

Here are concise answers to the most common inquiries regarding AltStore troubleshooting and functionality.

Specifically, we address concerns regarding safety, compatibility, and account limitations that users frequently encounter.

Is it safe to use my main Apple ID with AltStore?

Generally, yes, it is considered safe to use your main Apple ID because AltStore only sends your credentials directly to Apple’s servers for authentication purposes. However, for maximum privacy and to avoid any potential risk to your primary account data, many users prefer to create a secondary “burner” Apple ID specifically for sideloading activities.

Why do apps installed via AltStore expire after 7 days?

This limitation is enforced by Apple, not AltStore. For free developer accounts (standard Apple IDs), Apple only allows sideloaded certificates to remain valid for 7 days. AltStore attempts to circumvent this by automatically refreshing the apps in the background before they expire, provided your device and computer are connected to the same Wi-Fi.

Can I install more than three apps using AltStore?

No, you cannot typically exceed the three-app limit with a free Apple ID. Apple restricts free accounts to three active sideloaded apps at any one time, and AltStore itself counts as one of these apps. To bypass this limit, you would need to purchase a paid Apple Developer account, which costs $99 per year, or use the “Deactivate” feature in AltStore to swap active apps.