If you install this plugin first and then install the blog plugin you will encounter a bug. I think that this plugin forgets to check if the right columns have been created for the blog plugin. The result is and error message when saving a new blogpost and when trying to remove this plugin:

"SQLSTATE[HY000]: General error: 1 table rainlab_blog_posts has no column named seo_title"

I have a similar issue. The problem is that the extension relies on the Blog plugin and modifies it's db tables. I have both Blog and SEO Extension added to a project and when I attach the project to a fresh install it fails to install because SEO Extension tries to alter tables that doesn't exist. The implementation should probably be changed so that it doesn't change other plugin's tables but instead reference them from it's own tables.

A plugin can depend upon other plugins by defining a $require property in the Plugin registration file, the property should contain an array of plugin names that are considered requirements.

See: http://octobercms.com/docs/plugin/registration#dependency-definitions

marijnhurkens6645 said:

If you install this plugin first and then install the blog plugin you will encounter a bug. I think that this plugin forgets to check if the right columns have been created for the blog plugin. The result is and error message when saving a new blogpost and when trying to remove this plugin:

"SQLSTATE[HY000]: General error: 1 table rainlab_blog_posts has no column named seo_title"

you must be run this command after installation

php artisan plugin:refresh anandpatel.seoextension

The plugin's migration only check if RainLab.Blog is present in the project. But doesn't check if rainlab_blog_posts table exists. So when I run october:migrate while deploying existing project this plugin sees RainLab.Blog is present and is trying to alter rainlab_blog_posts table. But RainLab.Blog's migrations were not applied yet.