I have an old page hosted on GitHub pages. Use GitHub Pages custom domain and enforce HTTPS about 2 years. But last month when I access the page. I got this.

Err

ERR_CERT_COMMON_NAME_INVALID

That’s pretty weird. I didn’t change anything but it broke. why?

GitHub_Pages_Error_Message

After searching the error message. I found that GitHub has changed the IP for DNS point.

Here’s the DNS record.

$ dig +noall +answer mygithubpages.tw
mygithubpages.tw.		1798	IN	A	185.199.110.153
mygithubpages.tw.		1798	IN	A	185.199.108.153
mygithubpages.tw.		1798	IN	A	185.199.111.153
mygithubpages.tw.		1798	IN	A	192.30.252.153
mygithubpages.tw.		1798	IN	A	185.199.109.153
mygithubpages.tw.		1798	IN	A	192.30.252.154

Remove all 192.xxx record and make sure four 185.xxx record is active.

Update_DNS_record

$ dig +noall +answer mygithubpages.tw
mygithubpages.tw.		1798	IN	A	185.199.110.153
mygithubpages.tw.		1798	IN	A	185.199.108.153
mygithubpages.tw.		1798	IN	A	185.199.111.153
mygithubpages.tw.		1798	IN	A	185.199.109.153

After changing the value of A record. Everything back and peace.