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SSL certificate problem: unable to get local issuer certificate

This is a common problem when using Avast antivirus and others but sometimes also happens with some cURL versions.

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Solving problems with cURL

You can check if your CA bundle is up to date by running composer diagnose -vvv. Look for Checked CA file ... or Checked directory ... and you’ll see where Composer is looking for your CA bundle. You can get a new Certificate from cURL if this is a problem.

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Mitigating antivirus issues

If using a different CA bundle doesn’t help, you can try disabling antivirus and firewall to see if that helps. There are verified issues with Avast and others and they block Composer – there’s nothing that we can do with Herd to solve this problem, but you can disable HTTPS scanning in your antivirus software.

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Avast

In Avast, please go to “Protection > Core Shields > Web Shield > uncheck Enable HTTPS scanning” and that should help.

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Norton

In Norton, please go to “Security > Advanced > Safe Web > Settings” and disable HTTPS scanning and QUIC/HTTP3 scanning. If changing the settings in your antivirus software does help, please report this to your antivirus vendor so that they can implement a fix and allow enabling these protections again. You can read more about this at the official Composer docs.