Encountered [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found" on CentOS6.7

While trying to set up Zabbix, I encountered the following error, which rendered yum unusable.

http://mirror.centos.org/centos/6/SCL/x86_64/repodata/repomd.xml: [Errno 14] PYCURL ERROR 22 - "The requested URL returned error: 404 Not Found"
Trying other mirror.
Error: Cannot retrieve repository metadata (repomd.xml) for repository: scl. Please verify its path and try again

Faced with this, I was quite disheartened due to my limited OS knowledge, but the following link was helpful and led to a solution, so I am sharing it.

[tips][Linux] When you can't update yum on older versions of CentOS

Incidentally, I couldn't install Zabbix due to complications with PHP settings...

Programs like server monitoring tools or profilers that need to be installed on servers have a high barrier to entry at the installation stage...