[https] How do I fix certificate errors when running wget on an HTTPS URL in Cygwin?

For example, running wget https://www.dropbox.com results in the following errors:

ERROR: The certificate of `www.dropbox.com' is not trusted.
ERROR: The certificate of `www.dropbox.com' hasn't got a known issuer.

Just do

apt-get install ca-certificate

I have the similar problem and fixed it by temporarily disabling my antivirus(Kaspersky Free 18.0.0.405). This AV has HTTPS interception module that automatically self-sign all certificates it finds in HTTPS responses.

Wget from Cygwin does not know anything about AV root certificate, so when it finds that website's certificate was signed with non trust certificate it prints that error.

To fix this permanently without disabling AV you should copy the AV root certificate from Windows certificate store to /etc/pki/ca-trust/source/anchors as .pem file(base64 encoding) and run update-ca-trust

If the problem is that a known root CA is missing and when you are using ubuntu or debian, then you can solve the problem with this one line:

sudo apt-get install ca-certificates

May be this will help:

wget --no-check-certificate https://blah-blah.tld/path/filename

If you don't care about checking the validity of the certificate just add the --no-check-certificate option on the wget command-line. This worked well for me.

NOTE: This opens you up to man-in-the-middle (MitM) attacks, and is not recommended for anything where you care about security.

If you are using windows just go to control panel, click on automatic updates then click on Windows Update Web Site link. Just follow the step. At least this works for me, no more certificates issue i.e whenever I go to https://www.dropbox.com as before.

I had a similar problem with wget to my own live web site returning errors after installing a new SSL certificate. I'd already checked several browsers and they didn't report any errors:

wget --no-cache -O - "https://example.com/..." ERROR: The certificate of ‘example.com’ is not trusted. ERROR: The certificate of ‘example.com’ hasn't got a known issuer.

The problem was I had installed the wrong certificate authority .pem/.crt file from the issuer. Usually they bundle the SSL certificate and CA file as a zip file, but DigiCert email you the certificate and you have to figure out the matching CA on your own. https://www.digicert.com/help/ has an SSL certificate checker which lists the SSL authority and the hopefully matching CA with a nice blue link graphic if they agree:

`SSL Cert: Issuer GeoTrust TLS DV RSA Mixed SHA256 2020 CA-1

CA: Subject GeoTrust TLS DV RSA Mixed SHA256 2020 CA-1 Valid from 16/Jul/2020 to 31/May/2023 Issuer DigiCert Global Root CA`

First, the SSL certificates need to be installed. Instructions (based on https://stackoverflow.com/a/4454754/278488):

pushd /usr/ssl/certs
curl http://curl.haxx.se/ca/cacert.pem | awk 'split_after==1{n++;split_after=0} /-----END CERTIFICATE-----/ {split_after=1} {print > "cert" n ".pem"}'
c_rehash

The above is enough to fix curl, but wget requires an extra symlink:

ln -sT /usr/ssl /etc/ssl

apt-get install ca-certificates 

The s makes the difference ;)