How to debug ERR_PROXY_CERTIFICATE_INVALID?
I am trying to encrypt communication between Chrome with a squid forward proxy. I provided a self-signed certificate and clearly something is wrong with it because Chrome fails with ERR_PROXY_CERTIFICATE_INVALID.
Yes, I have installed the self-signed certificate into the Trusted Root Certification Authorities.
Is there a way to get a hint from Chrome regarding what it did not like about the certificate?
asked Sep 18 ’20 at 5:18
I ended up filing a bug report for this issue and their suggestion was to:
Disable the proxy configuration in chrome
Hit the proxy server as if it was a webpage
The conventional error dialog will display allowing you to debug the certificate error.
For example, if your proxy is listening to on port 1234 then you should hit in Chrome without the use of a proxy.
Secondly, I ended up figuring out the problem with my particular certificate. My proxy server does not have a public hostname, just a public IP address.
I was generating the certificate like this:
openssl req -x509 -newkey rsa:4096 -sha256 -days 365 -nodes -keyout -out -subj /CN=
It turns out that if Chrome references a proxy server by IP address (not hostname) then you must omit the DNS entry from the SSL certificate. The following command-line worked for me:
openssl req -x509 -newkey rsa:4096 -sha256 -days 365 -nodes -keyout -out -subj /CN=
answered Sep 27 ’20 at 2:55
GiliGili1, 6814 gold badges22 silver badges36 bronze badges
Not the answer you’re looking for? Browse other questions tagged windows google-chrome proxy ssl certificate or ask your own question.
“This webpage is not available” – Chromebook Help – Google Support
Send feedback help content & informationGeneral Help Center experience This message means Google Chrome couldn’t find and load the webpage you’re trying to visit. To fix the problem, try the steps below.
Check the web address
If you see the message “ERR_NAME_NOT_RESOLVED” or “ERR_CONNECTION_REFUSED” in your browser window, try these steps:
Check the web address (URL) in the address bar to make sure you’re going to the right webpage.
If you are, try to open the same webpage on another computer connected to the same network.
If you can’t see the webpage on any computer, check if you’re connected to the Internet. If you are, the webpage might be down.
Delete your cookies
Cookies are files created by websites you’ve visited to store browsing information, such as your profile or preferences for the website. Sometimes, a broken cookie file can cause errors.
On your computer, open Chrome.
At the top right, select More.
Select More tools Clear browsing data
Select a time range Cookies and other site data Clear data.
Change your proxy settings
If the browser takes a long time to load a webpage or search, it might be using a web proxy. If you see the message “Resolving proxy” or “ERR_PROXY_CONNECTION_FAILED” in your browser window, you can change your proxy settings.
At the bottom right, select the time.
In the “Network” section, select the network you’re using.
Select the network name again.
Change your proxy settings.
Changing your proxy settings might break your connection to the web. If you’re not sure what settings to use, contact your network administrator. Also, proxies that need to be authenticated don’t work with Chromebooks.
Note: If you’re using your Chromebook at work or school, you won’t be able to change your proxy settings. For more help, contact your administrator.
Was this helpful? How can we improve it?
Troubleshooting – HTTP Toolkit
Sometimes things go wrong. Below is a list of known issues you might encounter with HTTP Toolkit, and what you can do about them.
Have any issues not listed here? Please get in touch, either by email or by filing an issue on GitHub.
HTTP Toolkit doesn’t start
There’s a few known possible causes of this:
The ports HTTP Toolkit uses are in use. HTTP Toolkit uses ports 45456 and 45457 for internal communication, and then selects a separate port for the proxy automatically. If one of those ports is in use, or there are no free ports available, HTTP Toolkit will fail to start.
A previous run of HTTP Toolkit has crashed without cleaning up after itself, and is still using these ports. To resolve this, you will need to kill the background toolkit-server node process.
Your local install has become corrupted somehow. Reinstalling the latest version of the app should generally resolve this.
If you hit this issue, please get in touch. Right now there’s no well known applications using these ports, so all these possibilities are very unusual, and it’s possible that they’ll be solvable with more investigation.
HTTP Toolkit starts, but blank
HTTP Toolkit loads its UI and the core of its logic from on first startup, and updates automatically as new versions of that site become available.
That means on the first startup you will need an internet connection, and if you’re offline HTTP Toolkit will not start successfully.
This is only required for the first start – after that the latest UI is stored indefinitely, so that future startups will work offline, and load much more quickly.
The server crashes and the app restarts
Any time the server crashes, a notification is shown with the error details and the app is restarted (up to 3 times, and only if the server ran for at least 5 seconds before crashing).
If you’re seeing this, you’ve found something that completely crashes the running server. It might be some very unusual HTTP traffic, a specific use of an interceptor, or something else, but regardless please get in touch with any details you have, as this is definitely a bug that needs fixing.
I hate Electron
This is a whole debate that we can get into elsewhere, but if you really don’t like Electron apps, it is possible to use HTTP Toolkit without it. To do so:
Start a server:
Download the latest HTTP Toolkit server from for your platform
Extract it somewhere
Run. /bin/toolkit-server start in the extracted folder
Open in Chrome, Edge, Brave or Firefox:
This is the hosted version of the latest HTTP Toolkit UI
A Chromium or Firefox-based browser is required, as Safari has issues with some of the UI/server communication
The UI will work offline in your browser after the first load, just like the app, as it’s built using service workers
Firefox shows ‘Unable to connect’ or ‘EConnRefused’
In some circumstances, initial Firefox setup can fail with this error, and something like “Firefox can’t establish a connection to the server at localhost:8001″.
This is quite rare, and the exact cause isn’t pinned down yet. In general this will disappear immediately if you close Firefox and try again.
If you can reproduce this issue reliably, please get in touch, so we can trace down the exact cause of this.
A browser shows ERR_PROXY_CERTIFICATE_INVALID or other certificate errors
This means that your browser is not correctly trusting the HTTP Toolkit certificate it has been given, for some reason.
This is another very rare issue, and it’s unclear why this happens on certain machines. If this happens to you, do please get in touch so we can investigate it further.
In the meantime you can manually start Chrome configured to trust all certificates with the below command (for Windows):
–ignore-certificate-errors –user-data-dir=”C:Users$YOURUSERNAMEAppDataLocaltoolkitConfigchrome” –proxy-server=127. 0. 1:8000 –proxy-bypass-list=”<-loopback>;localhost:8000″ –disable-restore-session-state –no-default-browser-check –disable-popup-blocking –disable-translate –start-maximized –disable-default-apps –disable-sync –enable-fixed-layout –no-first-run –noerrdialogs –flag-switches-begin –flag-switches-end
You will need to use the full path for Chrome on your machine, and use your username instead of $YOURUSERNAME here.
This issue has only been seen on Windows, but if you do see this on Mac or Linux, you’ll need to update the data dir path completely. Any empty directory is fine, it’s only used to store the new Chrome’s profile, and the directory can be deleted later.
An application I have installed appears as ‘Not Available’
HTTP Toolkit attempts to detect which relevant applications you have installed when it’s started, so it can show the available ones in the UI.
If this isn’t working in your case, it’s possible there’s something unusual in your configuration. Please report this so it can be fixed properly.
In the meantime, if you’re trying to launch a browser, you can manually edit or delete the cached list of detected browsers at:
Adding your browser of choice in there or fixing the detected settings should get it to appear the next time you start the app.
Interception doesn’t work in some other way
If you need to test whether any client is working correctly, make a request to You should see “You’re not being intercepted” or “You’re being intercepted”, depending on whether your traffic is successfuly going through HTTP Toolkit
If you’re struggling to manually set up a client, there’s two possibilities: either the client isn’t using the HTTP proxy settings correctly, or it doesn’t trust the certificate. In the former case, you should see “You’re not being intercepted” when making requests to In the latter case, you’ll likely receive certificate errors, and you should be able to see rows showing failed or rejected requests on the View page.
Terminal interception should be available on all machines, but it’s possible that browser and other interception options might not be available on your machine, depending on the applications you have installed. Ensure you have the required applications correctly installed on your system. Installing applications in unusual locations or in portable/standalone modes may stop them being automatically detected.
Frequently Asked Questions about err_proxy_certificate_invalid chrome
How do I fix proxy error on chrome?
If you see the message “Resolving proxy” or “ERR_PROXY_CONNECTION_FAILED” in your browser window, you can change your proxy settings.At the bottom right, select the time.Select Settings .In the “Network” section, select the network you’re using.Select the network name again.Select Proxy.Change your proxy settings.
What does Err_proxy_certificate_invalid mean?
A browser shows ERR_PROXY_CERTIFICATE_INVALID or other certificate errors. This means that your browser is not correctly trusting the HTTP Toolkit certificate it has been given, for some reason. This is another very rare issue, and it’s unclear why this happens on certain machines.
How do I get rid of SSL error in chrome?
Clear Browser Cache. Open Google Chrome and press Cntrl + H to open history. … Disable SSL/HTTPS Scan. … Enable SSLv3 or TLS 1.0. … Correct your Date and Time. … Clear SSL Certificate Cache. … Clear Internal DNS Cache. … Reset Internet Settings. … Update Chrome.More items…