Incompatible API behavior during Grunt 0.4 to 1.x migration

Gruntfile.js Compatibility

Migrating a build pipeline from Grunt 0.4 to version 1.x introduces significant changes to the task runner's API. While the core functionality remains similar, the internal mechanisms for task registration and configuration handling have evolved, leading to failures when legacy Gruntfiles are executed in a 1.x environment.

Because the project maintainers did not provide an automated migration path, developers must manually rewrite configuration blocks to align with current API specifications. This process creates uncertainty regarding which specific task definitions are deprecated and which remain backward compatible.

What are the primary API breaking changes between Grunt 0.4 and 1.x that necessitate a manual rewrite of the Gruntfile.js? Which specific configuration patterns from 0.4 are no longer supported in 1.x?