The browser says NET::ERR_CERT_AUTHORITY_INVALID
How do I fix 'NET::ERR_CERT_AUTHORITY_INVALID' on my laptop?
Written by The CommonFixes team · fact checked by CommonFixes review desk
Last updated
Short answer
Every secure site presents a certificate signed by an authority your computer already trusts. This code means the signature leads back to an issuer your machine does not recognise. That happens when antivirus inspects secure traffic with its own certificate, when a public network intercepts the connection before you sign in, when the list of trusted issuers is out of date, or when adware has installed a certificate of its own. The quickest thing to try first: test the same page on another device — If your phone on mobile data loads the site normally, the fault is on this computer or this network, not the website. That one check saves a lot of wasted effort. Most people are done in about 20 minutes.
Full walkthrough below: 7 steps for Windows and Mac, rated medium.
Sounds like this
- •Your connection is not private, with that exact code
- •The same page opens fine on your phone
- •It appears on many sites at once, not just one
Why it happens
Every secure site presents a certificate signed by an authority your computer already trusts. This code means the signature leads back to an issuer your machine does not recognise. That happens when antivirus inspects secure traffic with its own certificate, when a public network intercepts the connection before you sign in, when the list of trusted issuers is out of date, or when adware has installed a certificate of its own.
Work through these in order
0% done- 1
Test the same page on another device
If your phone on mobile data loads the site normally, the fault is on this computer or this network, not the website. That one check saves a lot of wasted effort.
- 2
Finish signing in to the network you are on
Hotel, cafe and airport networks intercept the first connection to show a sign in page. Open a plain page such as neverssl.com, complete the sign in, then reload the site you wanted.
- 3
Check the date and time
Windows: Settings, Time and language, Date and time, and press Sync now. Mac: System Settings, General, Date and Time, and turn on Set time and date automatically. A clock that is wrong makes valid certificates look untrustworthy.
- 4
Turn off HTTPS or SSL scanning in your antivirus
Avast, AVG, Kaspersky, ESET and Bitdefender all have a setting named something like Encrypted connections scanning, HTTPS scanning or Web shield. Turn it off, restart the browser and try again. This is the most common single cause on Windows laptops, because the antivirus signs pages with a certificate the browser does not always accept.
- 5
Look at who actually issued the certificate
Press the icon to the left of the address, choose Connection is not secure, then Certificate is not valid, and read the Issued by line. If it names your antivirus, the previous step is the fix. If it names something you do not recognise, treat it as adware and run a scan with Malwarebytes.
- 6
Update your browser and Windows
The list of trusted authorities is refreshed through updates. Open Help, About in your browser to update it, and install pending Windows updates. Machines that have been switched off for a long time commonly show this on many sites at once.
- 7
Clear the browser's certificate state
In Chrome or Edge open Settings, Privacy and security, Delete browsing data, choose All time and tick Cached images and files along with Cookies. Then restart the browser fully rather than only closing the tab.
If none of that worked
Never tick the option to proceed on a banking, email or shopping site while this warning shows, because you cannot tell who is on the other end. If only one site is affected everywhere you try, the site owner has configured their certificate incorrectly and it is their job to fix it.
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Who wrote this and how we checked it
The CommonFixes team
Writer and researcher
We are a small group of people who spend our days repairing laptops and desktops for family, friends and small offices. Every guide here starts with a problem someone actually brought to us, and we only write down the steps that put the machine right.
- Everyday repairs
- Windows and Mac
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CommonFixes review desk
Technical editor
Before a guide goes live, a second person walks through it on a real machine and checks each instruction against the maker's own support pages. Anything we cannot confirm is removed rather than guessed at.
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This guide was last updated on 10 August 2026. If a step no longer matches what you see on screen, tell us on the contact page and we will test it again.
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