In the world of mobile repair and firmware flashing, the "Handshaking... Error Unexpected Response 0x68" is a common hurdle, often seen when using tools like UnlockTool to bypass FRP or flash Android devices. The Troubleshooting Story
Imagine you're trying to flash a device. You've connected everything, but the software hangs at "Handshaking" and throws error . Here is how to resolve it: Check the "Handshake" Cable
The "handshake" is the initial communication between your PC and the phone's BootROM. Error 0x68 often means the signal is weak or interrupted. Use a high-quality, original USB cable and avoid using front-panel USB ports on desktop computers—plug directly into the motherboard ports at the back. Driver Conflicts
If your PC "sees" the device but doesn't understand its response, it’s likely a driver issue. Ensure you have the latest MTK/SPD drivers installed. Many users find success by using a "Filter" in LibUSB-win32
to specifically capture the device's connection during the handshake phase. Force the Connection (The Key Combo)
Handshaking often fails if the device isn't in the correct mode (like BROM mode for MTK chips). Volume Up + Volume Down
while plugging in the USB cable. This "forces" the handshake to happen on the correct port. Software Environment
Sometimes, antivirus software or other phone managers (like iTunes or Samsung Smart Switch) interfere with the serial port communication. Disable these temporarily to give your flashing tool exclusive access to the USB port. If you’d like more specific help, let me know: are you using (e.g., UnlockTool, SP Flash Tool)? What is the of the phone?
were you trying to perform (e.g., Factory Reset, FRP Bypass, Flashing)?
I can give you the exact "button combo" or driver link for your specific device. How To Fix Unlocktool Handshaking Failed Error Fix 17 Jun 2025 —
Troubleshooting the "Handshaking... Error Unexpected Response 0x68"
If you’re staring at a terminal or log file and seeing the cryptic message handshaking... error unexpected response 0x68, you’ve likely hit a wall while trying to establish a connection. Whether you’re working with VPNs (like OpenVPN or WireGuard), flashing firmware on an ESP32/Arduino, or configuring a network gateway, this error is a classic "communication breakdown."
In hex code, 0x68 translates to the ASCII character 'h'. While that might seem random, it is a massive clue. What Does Error 0x68 Actually Mean? handshaking... error unexpected response 0x68
This error occurs during the "handshake" phase—the initial "hello" between a client and a server. The client sends a specific packet expecting a certain protocol response, but instead, the server sends back something else.
Because 0x68 is 'h', the most common reason for this error is that your client is trying to talk via an encrypted protocol (like SSL/TLS or a VPN tunnel), but the server is responding with plain HTTP.
The "h" usually comes from the first letter of "HTTP/1.1" or "html." Essentially, your device is expecting a secure handshake, but the server is just talking regular web language. Common Scenarios and Fixes 1. VPN Connections (OpenVPN / Stunnel)
This is the most frequent culprit. It usually happens when there is a mismatch between the port and the protocol.
The Cause: You are connecting to a port (like 443) expecting a VPN handshake, but a web server (Nginx/Apache) is sitting on that port instead. The Fix: Double-check your Remote IP and Port in your config file.
If you are using a proxy, ensure the proxy isn't intercepting the traffic and serving a "404 Not Found" or "403 Forbidden" page in HTML format. Verify that the server-side service is actually running. 2. Microcontrollers (ESP32 / ESP8266 / Arduino)
If you see this while flashing firmware or using an AT command set:
The Cause: The baud rate is mismatched, or the bootloader is receiving noise/web traffic instead of data. The Fix:
Lower your Baud Rate (e.g., from 115200 to 9600) to test stability.
Check your power supply. Insufficient voltage to the chip can cause "garbage" data to be sent back, which the computer misinterprets as 0x68. 3. SSL/TLS Mismatches
When a software library expects an encrypted stream but hits a captive portal (like a hotel Wi-Fi login page):
The Cause: The "Unexpected Response 0x68" is actually the beginning of the tag from the login redirect page. In the world of mobile repair and firmware
The Fix: Open a browser on the device to see if you are being redirected to a login or "Terms of Service" page. Once you "sign in" to the network, the handshake error should disappear. 4. Proxy and Firewall Interference
The Cause: Corporate firewalls or "Deep Packet Inspection" (DPI) tools often intercept unauthorized handshakes and inject a reset or an informative HTML block.
The Fix: Try changing your connection port to UID 53 (DNS) or 443 (HTTPS), or use a bridge to obfuscate the handshake. Summary Checklist
Is the Port correct? Ensure the service on the other end is actually what you think it is.
Is there a Captive Portal? Check if the network requires a browser login.
Protocol Mismatch: Are you sending TCP to a UDP port, or TLS to an HTTP port?
Check the Logs: Look at the server-side logs. If the server says "Invalid Request," the client is the problem. If the server log is empty, the traffic isn't even reaching it.
By recognizing that 0x68 is likely just the letter 'h' from an HTML response, you can stop looking for a complex hardware failure and start looking for a simple network redirection or configuration typo.
Are you seeing this error while setting up a VPN or while flashing a device via a serial port?
The error "handshaking... error unexpected response 0x68" is a specific technical failure often seen when using the Unlock Tool or similar mobile service software to communicate with Android devices (typically those with MediaTek/MTK or Spreadtrum/SPD chipsets) in BROM or Preloader mode. Technical Breakdown
The hex code 0x68 typically represents a communication mismatch where the tool expects a specific "Hello" or "Handshake" response from the device's bootloader but receives an unexpected byte.
Handshaking: The initial phase where the software and hardware agree on protocol parameters. Log raw hex – Capture exactly what is sent and received
0x68: This specific response often indicates that the device has already booted past the required stage or that the connection was interrupted by a driver conflict. Potential Causes & Fixes
Driver Conflicts: This is the most common cause. Old or incompatible USB VCOM/MTK drivers can send incorrect signals. Updating or reinstalling the libusb-win32 filter is often recommended to capture the device correctly.
Incorrect Boot Mode: The device must be in a "dead" or "forced" state to accept the handshake. If the device reboots too quickly or shows a charging icon, the tool will trigger this error.
Physical Connection: Low-quality USB cables or damaged ports can cause byte-level errors during the handshake.
Server Lag: Since tools like Unlock Tool require an active server connection to validate the handshake, high latency can lead to a timeout that looks like a response error. Review for Developers/Users
If you are developing a review or documentation for this tool:
Ease of Use: Note that while the interface is streamlined, the reliance on specific driver versions (like MTK drivers) makes it difficult for beginners.
Reliability: The 0x68 error is a frequent "pain point" in user forums, often requiring users to physically "test point" the device (shorting pins) to force the correct handshake response.
Support: The tool is highly effective for FRP (Factory Reset Protection) bypass, but documentation for specific error codes like 0x68 is often found in community groups rather than official manuals.
| Check | Action | |-------|--------| | Baud rate | Ensure matching rates (e.g., 9600, 19200, 57600). Try auto-baud detection if supported. | | Data bits | Usually 8. | | Parity | Even, Odd, or None – must match device config. | | Stop bits | 1 or 2. | | Flow control | Disable hardware handshake (RTS/CTS) unless explicitly required. |
When you see "handshaking... error unexpected response 0x68", do not reboot everything randomly. Follow this forensic process.
TX: 01 03 00 00 00 01 84 0A
RX: 68
0x68.0x00 or 0xFF sent 20-50ms before real command.cutecom, RealTerm, or vendor-specific utility).