DataWeave 2.12.0 Release Notes

This MuleSoft programming language simplifies data transformation tasks and serves as Mule runtime’s expression language for configuring components and connectors. Build powerful integration solutions with intuitive scripting capabilities.

For more detail, see DataWeave Language.

June 2, 2026

DataWeave 2.12.0 is bundled with the Mule 4.12.0 release. For details about the Mule release, see Mule Runtime Engine 4.12.0 Release Notes.

What’s New

The 2.12.0 version of DataWeave introduces these new features and enhancements:

General improvements:

DataWeave incorporates new system properties. See DataWeave System Properties.
The UNLIMITED_CONTEXT math variable now has the precision=0 and roundingMode=HALF_UP properties.

Compatibility

This table specifies which version of DataWeave is bundled with each Mule runtime engine release:

Mule Version	DataWeave Version
4.11	2.11
4.10	2.10
4.9	2.9
4.8	2.8
4.7	2.7
4.6	2.6
4.5	2.5
4.4	2.4
4.3	2.3
4.2	2.2
4.1	2.1
3.9	1.2
3.8	1.1
3.7	1.0

Fixed Issues

The release addresses these DataWeave issues and incorporates all patch updates from the 2.11.0 DataWeave release through May 2026:

Issue Resolution ID

Issue Resolution	ID
DataWeave now supports the `private` modifier on `fun`, `var`, `ns`, and `type` declarations to hide them from importers.	W-21148967
`internal` is no longer a reserved word and can now be used as an identifier in DataWeave scripts.	W-21508044
The compiler now reports an error when overloads of the same function declare different visibility modifiers.	W-21362539
`StackOverflowError` no longer occurs in the type checker when resolving intersections of unbound type parameters.	W-20124753
Runtime errors no longer occur when invoking overloaded functions across modules.	W-21811015
Spurious type-check errors no longer occur when an optional key-value pair is assigned to a required one.	W-21351058
`deferred` values passed to the `write` function now terminate correctly.	W-20925604
Out-of-memory errors no longer occur when reading large text or CDATA sections with the indexed XML reader.	W-21006104
The Java module bean introspection cache no longer causes memory leaks.	W-22419118

DataWeave now supports the private modifier on fun, var, ns, and type declarations to hide them from importers.

W-21148967

internal is no longer a reserved word and can now be used as an identifier in DataWeave scripts.

W-21508044

The compiler now reports an error when overloads of the same function declare different visibility modifiers.

W-21362539

StackOverflowError no longer occurs in the type checker when resolving intersections of unbound type parameters.

W-20124753

Runtime errors no longer occur when invoking overloaded functions across modules.

W-21811015

Spurious type-check errors no longer occur when an optional key-value pair is assigned to a required one.

W-21351058

deferred values passed to the write function now terminate correctly.

W-20925604

Out-of-memory errors no longer occur when reading large text or CDATA sections with the indexed XML reader.

W-21006104

The Java module bean introspection cache no longer causes memory leaks.

W-22419118

Upgrade

This version of DataWeave is bundled with Mule. DataWeave upgrades take place through Mule. See Mule Upgrades and Patch Updates.