MAAS 2.5 Release notes

Discourse is now the preferred location for release notes.

• MAAS 2.5.0 beta 4
• MAAS 2.5.0 beta 3
• MAAS 2.5.0 beta 2
• MAAS 2.5.0 beta 1
• MAAS 2.5.0 alpha 2
• MAAS 2.5.0 alpha 1