I sometimes get inquiries about implementation of the native Movable Type captcha system for comments, often from people who are on the same webhost as this site but cannot get the captchas to work.
You might just be in luck if you’re looking for a fix for the following message that appears at Blog Settings –> Comment settings –> Comment Display Options –> CAPTCHA Provider:
“You will need to speak to your host about Image::Magick and if it is installed.
CaptchaSourceImageBase is a configuration directive.”
As you can see, any really useful information is kind of left out, but a bit of Googling reveals the following: CaptchaSourceImageBase is simply a line that needs to be added to your mt-config.cgi file.
Specifically, edit your-path in the following and add to mt-config.cgi:
Hope that works for you.