Unable to resolve sequelize package

I had the same issue. I installed sequelize-cli forgetting to add sequelize itself:

npm install sequelize

In sequelize-cli package.json file, sequelize is mentioned as a devdependency which means it does not install it when you do npm install sequelize-cli. My guess is you have not installed sequelize itself and this is what the error says.

Unable to resolve sequelize package in /Users/bheng/Sites/BASE

install sequelize npm install --save sequelize (or global) and things should be good.

PS: Great answer on different dependencies and what they mean