JetBrains has released bug-fix updates for three major versions of its language workbench, MPS: 2025.3.1, 2025.2.3, and 2025.1.3[reference:5]. The updates address a range of issues across the platform, with the most notable change being a new read-only inspector style that applies the read-only property to all editor cells in the inspector[reference:6]. When this style is applied to a cell in the main editor, the inspector becomes read-only for the inspected node while that cell is selected.
What is MPS?
MPS, or the Meta Programming System, is a language workbench designed for creating domain-specific languages (DSLs)[reference:7]. It allows developers to design custom programming languages tailored to specific problem domains, reducing boilerplate code and improving productivity[reference:8]. Unlike traditional compilers or interpreters, MPS uses projectional editing — a technique where the editor directly manipulates the abstract syntax tree rather than text — which enables features like multiple notations for the same language and seamless language composition.
What the updates fix
The three releases are part of JetBrains' ongoing maintenance strategy for MPS. Each version branch receives targeted fixes that do not introduce new features, making them safe for teams who need stability over new capabilities. The full list of fixed issues is available for each version through JetBrains' issue tracker[reference:9]. The read-only inspector style fix in 2025.3.1 is the headline change, but the updates also include other stability improvements across the platform.
These bug-fix releases follow a pattern JetBrains has established with earlier MPS versions. In January 2026, the company released similar updates for MPS 2025.2.2 and 2025.1.2[reference:10], showing a commitment to maintaining multiple version tracks simultaneously. This approach gives teams flexibility: some organizations prefer to stay on an older version for compatibility reasons while still receiving critical fixes.
Why this matters
For teams building DSLs with MPS, these updates represent low-risk maintenance that keeps their toolchain stable without forcing an upgrade to a new major version. The read-only inspector fix, while small in scope, improves the user experience for developers working with complex editor configurations. And for organizations with strict change-control processes, having bug-fix releases across multiple version tracks means they can address issues without re-certifying an entire new release.
JetBrains continues to develop MPS actively. The company released MPS 2026.1 in July 2026 with major features including migration to IntelliJ Platform 2026.1, JDK 25, and Kotlin 2.3. The 2025.3.x branch represents the previous stable release track, and these bug fixes ensure it remains viable for teams who are not ready to move to 2026.1. The full release notes for each version are available on the JetBrains blog.