Summary: A solution for "pear/pecl is using a unsupported protocal (protocol)".
While trying to install the APC Opcode Cache on a server yesterday, when I tried to run this command:
pecl install apc
I kept getting this error message:
pecl.php.net is using a unsupported protocal -
This should never happen.
After doing some research, it looks like you can also get a similar error message with PEAR: