This is a maintenance release in the 1.3.x stable series. It has 19 fixes and improvements over 1.3.1. For more details see changelog.
Go ahead and download the release from our website.
MantisBT 1.2.20 (download) is the final maintenance and security release for the 1.2.x series. All installations that are currently running any 1.2.x version are strongly advised to upgrade to either 1.3.x (recommended) releases or 1.2.20.
This release includes 32 fixes (see changelog) with resolves 3 security and a couple of PHP 7 compatibility issues.
MantisBT 2.0.0 release focuses on improvements to the UI compared to 1.3.x release. As of this release, the db schema is the same between 1.3.x and 2.0.0-beta.1, enabling users to easily try 2.0.0-beta.1 and provide feedback.

Checkout the new release on mantisbt website and report any issues you may find via our official bugtracker.
This second and last 1.3.x release candidate has 127 bug fixes and improvements. Some of the highlights include:
Checkout the new release on mantisbt website and report any issues you may find via our official bugtracker.