jenkinsci/jenkins

Deleting an element from a "full" hetero(?) list does not re-enable the "Add" button

Open

#26737 opened on May 4, 2026

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good first issuelts-candidateregression

Description

Jenkins and plugins versions report

2.536+ Firefox

What Operating System are you using (both controller, and any agents involved in the problem)?

n/a

Reproduction steps

  1. Find a descriptor list that restricts adding new elements, e.g., a Freestyle job's "Add post-build action".
  2. Add all elements until all are added.
  3. Observe that the "Add post-build action" becomes disabled.
  4. Remove an element from the list

Expected Results

The "Add post-build action" becomes enabled.

Actual Results

It remains disabled until you click on it while it's disabled (???). This click can happen before or after you remove an element, but it only becomes enabled again when that element is removed.

Anything else?

In earlier releases (shown: 2.500) the button remained active even if all elements are disallowed.

In 2.530 and 2.535 (didn't look further) the button became disabled, but also correctly enabled once an element is removed.

In 2.536 and later, the button becomes disabled, but not enabled again until clicked. Likely caused by https://github.com/jenkinsci/jenkins/pull/10186.

Are you interested in contributing a fix?

No response

Contributor guide

Tech stack
javajavascript
Domain
frontend
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
None
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
65
Research direction
The issue notes that the bug was likely introduced by PR #10186. Investigate the changes in that PR, focusing on the hetero list UI component in Jenkins core. The fix likely involves updating the logic that enables/disables the 'Add' button when items are removed from a full list. Examine the JavaScript or Java code that handles the list state and ensure the button is re enabled after deletion.