How to fix Roblox “Bad Request” error code 400

What is Roblox “Bad Request” error code 400

Some users happen to see the “Bad Request” error code 400 while trying to launch Roblox in their browser(s). The issue indicates there is a connection issue between the game’s client and server that receives the request. Here is a full error message that users can see:

This issue may be related to corrupted browser files, incorrect network settings, damaged DNS server cache, and even problems on the side of the server itself. You can check whether Roblox severs experience any issues at the moment using the official Roblox Server Status or DownDetector. If everything seems fine with the server, then the connection issue may originate from your PC and should be resolved individually. Follow our guide below to try each solution and potentially fix the “Bad Request” error code 400.

1. Restart your router

We recommend you try and reset your internet connection by restarting the router (modem) if you have a possibility to do so. Hold the power button at the back of the router for a couple of seconds until it turns off. Then, push the same button to power it back. Simply restarting your router helps deal with a variety of problems. Try and see if it helps before moving further to the other solutions below.

2. Run Internet Connection Troubleshooter

If rebooting the router did not help, you can try the in-built Internet Connections Troubleshooter to detect and resolve connection-related issues. If any are found, Windows will automatically solve them and make sure Roblox runs smoothly without errors again. Here is how:

For Windows 10:

1. Right-click on Start Menu and open Settings. You can also press Windows key + I buttons instead.
2. Navigate to Update & Security > Troubleshoot.
3. On the right pane, go to Additional troubleshooter, locate Internet Connections and click Run the troubleshooter.
4. Finish the process following the on-screen instructions and restart your PC.
5. After this, try to open the Roblox page again.

For Windows 11:

1. Open Settings from the bottom taskbar.
2. Choose System on the left and go to Troubleshoot > Other troubleshooters on the right pane.
3. Then, find Internet Connections and click Run next to it.
4. Finish the process following the on-screen instructions and restart your PC.
5. After this, try to launch the game again.

3. Clear Web Browser Cache

Connection problems may sometimes be caused by junk/corrupted web files like cache and cookies that accumulate over time in the browser. Since Roblox is usually played in a browser, clearing browsing data may help alleviate the issue and let you bypass the error eventually. Here are instructions how to clear browsing data in Chrome, Firefox, and Edge browsers:

clear cache in Google Chrome:

1. Open Chrome and click on the three-dot icon in the top right corner.
2. Go to More tools and choose Clear browsing data….
3. At the top, choose a time range. To delete everything, select All time.
4. Check the boxes next to Cookies and other site data and Cached images and files.
5. Then click on Clear data.

Restart your browser and try to open Roblox again.

clear cache in Mozilla Firefox:

1. Open Firefox and click on the the three-line icon in the top right corner.
2. Go to Settings and select Privacy & Security on the left pane.
3. Click on Clear Data… next to the Cookies and Site Data section.
4. Select Cookies and Site Data and Cached Web Content and click Clear in the end. Then click Clear Now to confirm.

Restart your browser and try to open Roblox again.

clear cache in Microsoft Edge:

1. Open Microsoft Edge and click on the three-dot icon in the top right corner.
2. Go to Settings and select Privacy, search, and services on the left pane.
3. Under the Clear Browsing Data section click on Choose what to clear.
4. At the top, choose a time range. To delete everything, select All time.
5. Choose Browsing history, Download history, Cookies and other site data, and Cached images and files. Click Clear now.

Restart your browser and try to open Roblox again.

4. Reset TCP/IP

It is also possible that the issue occurs due to the incorrect TCP/IP configuration. TCP/IP is a set of fundamental protocols used to set up proper communication for the Internet and similar computer networks. Try to reset it using these steps below:

1. Find the Command Prompt by typing cmd into the searching box. Then right-click on it and choose Run as administrator.
2. In the opened window, you should paste these commands one-by-one by clicking Enter after each.

netsh winsock reset
netsh int ip reset

ipconfig /release
ipconfig /flushdns
ipconfig /renew

We hope this method will finally eliminate the problem.

5. Change address in DNS settings

Misconfigured communication between servers can also result from incorrect DNS settings. These configurations can sometimes change accidentally after certain changes. They may also be set to find the server automatically but ultimately fail to locate the correct one. Whatever the cause of the issue, you can try setting alternative DNS values as shown below:

1. Press Windows key + R and copy-paste ncpa.cpl. Press Enter to open.
2. Right-click on your connection name.
3. Click on Properties.
4. Double click on Internet Protocol Version 4 (TCP/IPv4).
5. Mark Use the following IP address and Use the following DNS server addresses.
6. Change IP address, Subnet mask, Default gateway, and DNS according to the underneath image



As an alternative, you may also change your DNS address to 1.1.1.1 and 1.0.0.1 is the former two on the screenshot above do not resolve the issue.

6. Disable Proxy in Local Area Network (LAN) Settings

If you have enabled a Proxy server connection in Windows LAN Settings, then this can be a reason for facing “Bad Request” error code 400 when launching Roblox. You can check it and disable the proxy setting in case it is enabled (especially if you remember doing so on purpose). We also advise you to turn off any third-party VPN software to make sure it does not affect your connection in any way at the time of checking. VPN software may also lead to similar connection issues.

1. Open search box next to Start menu and type Control Panel. Open it up.
2. Make sure View by is set to either Small Icons or Big Icons in the top right corner.
3. Select Internet Options and navigate to Connections & LAN settings.
4. Make sure there is only Automatically detect settings enabled. Unpick the other 2 boxes if they are selected, and click OK in the end.
5. Now you should have LAN settings set up correctly. Go to the browser and try to check the result.

7. Restore Windows Defender Firewall Settings to Default

If none of the previous methods showed success in eliminating the issue, then our last suggestion is to roll the firewall settings of Windows Defender back to their defaults. Custom firewall changes could prevent proper server communication. Thus, resetting firewall back to its default configuration may fix the problem. Follow these steps:

1. Type Windows Defender Firewall in search loop and press Enter to open it up. Alternatively, you can also press Windows key + R and copy-paste firewall.cpl.
2. Once opened, click on Restore defaults on the left pane.
3. Then click on Restore defaults and click Yes to confirm.
4. After doing so, go to Advanced settings on the left pane.
5. In the opened window, find and click on Restore Default Policy on the right pane. Confirm by clicking Yes.
6. Once the restoration has finished, click OK.

Summary

Roblox is not the only web application/game that may experience such connection errors. Other websites may also be subject to similar issues that prevent users from opening and using them. Therefore, you can use the solutions from our guide to fix other similar issues as well. We hope the “Bad Request” error code 400 is no longer targetting your while trying to play Roblox.