# Change in d2:validatePattern evaluation: please review your program rules

**URL:** <https://community.dhis2.org/t/change-in-d2-validatepattern-evaluation-please-review-your-program-rules/77634>\
**Category:** App Transition and Version Upgrades\
**Tags:** tracker, android\
**Created:** [20 October 2026 18:28 UTC](https://community.dhis2.org/t/change-in-d2-validatepattern-evaluation-please-review-your-program-rules/77634 "2026-10-20T18:28:35Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![nancyesp](https://dhis2.b-cdn.net/user_avatar/community.dhis2.org/nancyesp/32/32641_2.png) [@nancyesp](https://community.dhis2.org/u/nancyesp)\
**Post date:** [20 October 2026 18:28 UTC](https://community.dhis2.org/t/change-in-d2-validatepattern-evaluation-please-review-your-program-rules/77634/1 "2026-10-20T18:28:35Z")

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Hi everyone,  
We want to make you aware of a change that may affect existing program rules using `d2:validatePattern`.

**What changed**  
The way `d2:validatePattern` handles escaping in regular expressions was fixed ([DHIS2-21359](https://dhis2.atlassian.net/browse/DHIS2-21359)). The fix is included in:

- Android Capture app **3.4.2** and later, through an update of the expression parser
- DHIS2 server patch versions **2.41.9, 2.42.6, 2.43.2** and **2.44**

The change is intended and makes evaluation correct and consistent. However, some patterns that worked before may now evaluate differently. This is most likely for patterns that relied on the previous escaping behavior, such as sequences with backslashes like `\\b`.

The documentation has been updated to reflect this change and explain how it may affect existing program rules.

**What you might notice**  
Rules that used to trigger no longer do, or the other way round. For example, a field that should be shown after selecting an option stays hidden.

**How to find affected rules**  
You can list program rules whose condition uses the function with this API call:

```auto
/api/programRules?filter=condition:like:validatePattern&fields=id,name,condition,program[name]&paging=false

```

Program rule actions can also use it, for example in ASSIGN expressions:

```auto
/api/programRuleActions?filter=data:like:validatePattern&fields=id,data,programRule[name]&paging=false

```

If possible, consider reviewing patterns that rely on escaping and simplifying them where appropriate. For example, a pattern such as `\\d{6}\/\\d{2}` could potentially be rewritten as `[0-9]{6}/[0-9]{2}`, avoiding backslashes while preserving the intended matching behavior.

---

<div class="post-metadata">

**Author:** ![Matthew\_Boddie](https://dhis2.b-cdn.net/user_avatar/community.dhis2.org/matthew_boddie/32/34043_2.png) [@Matthew\_Boddie](https://community.dhis2.org/u/Matthew_Boddie)\
**Post date:** [22 October 2026 19:17 UTC](https://community.dhis2.org/t/change-in-d2-validatepattern-evaluation-please-review-your-program-rules/77634/2 "2026-10-22T19:17:19Z")

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We did notice this but, as you have noted, have removed the backslash format and transitioned all regex to the [0-9]{2} style, which has normalized the experience across old and new versions. Thanks for the update and context!