Assigning values to variables in env is broken

[cknowlto]

Jenkins and plugins versions report

Environment

Jenkins: 2.541.1
OS: Linux - 4.18.0-553.89.1.el8_10.x86_64
Java: 21.0.9 - Amazon.com Inc. (OpenJDK 64-Bit Server VM)
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What Operating System are you using (both controller, and any agents involved in the problem)?

Operating system = Linux decaf 3.10.0-1160.142.1.el7.x86_64 jenkinsci/jenkins#1 SMP Tue Oct 28 11:22:35 EDT 2025 x86_64 x86_64 x86_64 GNU/Linux

Reproduction steps

1. Create new pipeline job.
2. Use code:

pipeline {
    agent any
    environment {
        // Initial value (treated as a string 'true')
        MY_FLAG = 'true'
        MY_OTHER_FLAG = 'false'
        MY_BAD_FLAG = true
        MY_OTHER_BAD_FLAG = false
    }
    stages {
        stage('Check initial values as strings') {
            steps {
                script {
                    // Access and print the initial value (string)
                    echo "Initial flag value MY_FLAG: ${env.MY_FLAG}" 
                    echo "Initial flag value MY_OTHER_FLAG: ${env.MY_OTHER_FLAG}" 
                    echo "Initial flag value MY_BAD_FLAG: ${env.MY_BAD_FLAG}" 
                    echo "Initial flag value MY_OTHER_BAD_FLAG: ${env.MY_OTHER_BAD_FLAG}" 
                }
            }
        }
        stage('Change values') {
            steps {
                script {
                    // Change the value within the script block
                    env.MY_FLAG = 'false'
                    env.MY_OTHER_FLAG = 'true'
                    env.MY_BAD_FLAG = false
                    env.MY_OTHER_BAD_FLAG = true
                    echo "Updated local flag value MY_FLAG: ${env.MY_FLAG}" 
                    echo "Updated local flag value MY_OTHER_FLAG: ${env.MY_OTHER_FLAG}" 
                    echo "Updated local flag value MY_BAD_FLAG: ${env.MY_BAD_FLAG}" 
                    echo "Updated local flag value MY_OTHER_BAD_FLAG: ${env.MY_OTHER_BAD_FLAG}" 
                }
            }
        }
        stage('Global values') {
            steps {
                script {
                    echo "Updated global flag value MY_FLAG: ${env.MY_FLAG}" 
                    echo "Updated global flag value MY_OTHER_FLAG: ${env.MY_OTHER_FLAG}" 
                    echo "Updated global flag value MY_BAD_FLAG: ${env.MY_BAD_FLAG}" 
                    echo "Updated global flag value MY_OTHER_BAD_FLAG: ${env.MY_OTHER_BAD_FLAG}" 
                }
            }
        }
    }
}

Expected Results

Running on [build-300](https://jenkins.sdsp.mc.xerox.com:8443/computer/build%2D300/) in /opt/jenkins/workspace/ProblemTicket
[Pipeline] {
[Pipeline] withEnv
[Pipeline] {
[Pipeline] stage
[Pipeline] { (Check initial values as strings)
[Pipeline] script
[Pipeline] {
[Pipeline] echo
Initial flag value MY_FLAG: true
[Pipeline] echo
Initial flag value MY_OTHER_FLAG: false
[Pipeline] echo
Initial flag value MY_BAD_FLAG: true
[Pipeline] echo
Initial flag value MY_OTHER_BAD_FLAG: false
[Pipeline] }
[Pipeline] // script
[Pipeline] }
[Pipeline] // stage
[Pipeline] stage
[Pipeline] { (Change values)
[Pipeline] script
[Pipeline] {
[Pipeline] echo
Updated local flag value MY_FLAG: false
[Pipeline] echo
Updated local flag value MY_OTHER_FLAG: true
[Pipeline] echo
Updated local flag value MY_BAD_FLAG: whatever
[Pipeline] echo
Updated local flag value MY_OTHER_BAD_FLAG: whatever
[Pipeline] }
[Pipeline] // script
[Pipeline] }
[Pipeline] // stage
[Pipeline] stage
[Pipeline] { (Global values)
[Pipeline] script
[Pipeline] {
[Pipeline] echo
Updated global flag value MY_FLAG: false
[Pipeline] echo
Updated global flag value MY_OTHER_FLAG: true
[Pipeline] echo
Updated global flag value MY_BAD_FLAG: different whatever
[Pipeline] echo
Updated global flag value MY_OTHER_BAD_FLAG: different whatever

Actual Results

Running on [build-300](https://jenkins.sdsp.mc.xerox.com:8443/computer/build%2D300/) in /opt/jenkins/workspace/ProblemTicket
[Pipeline] {
[Pipeline] withEnv
[Pipeline] {
[Pipeline] stage
[Pipeline] { (Check initial values as strings)
[Pipeline] script
[Pipeline] {
[Pipeline] echo
Initial flag value MY_FLAG: true
[Pipeline] echo
Initial flag value MY_OTHER_FLAG: false
[Pipeline] echo
Initial flag value MY_BAD_FLAG: true
[Pipeline] echo
Initial flag value MY_OTHER_BAD_FLAG: false
[Pipeline] }
[Pipeline] // script
[Pipeline] }
[Pipeline] // stage
[Pipeline] stage
[Pipeline] { (Change values)
[Pipeline] script
[Pipeline] {
[Pipeline] echo
Updated local flag value MY_FLAG: true
[Pipeline] echo
Updated local flag value MY_OTHER_FLAG: false
[Pipeline] echo
Updated local flag value MY_BAD_FLAG: true
[Pipeline] echo
Updated local flag value MY_OTHER_BAD_FLAG: false
[Pipeline] }
[Pipeline] // script
[Pipeline] }
[Pipeline] // stage
[Pipeline] stage
[Pipeline] { (Global values)
[Pipeline] script
[Pipeline] {
[Pipeline] echo
Updated global flag value MY_FLAG: true
[Pipeline] echo
Updated global flag value MY_OTHER_FLAG: false
[Pipeline] echo
Updated global flag value MY_BAD_FLAG: true
[Pipeline] echo
Updated global flag value MY_OTHER_BAD_FLAG: false

Anything else?

I did not expect the assignments to work as booleans as env variables are clearly type string, but apparently NEITHER works. I have spend DAYS debugging conditional statements and long pipelines because of this.

This has to be new behavior. something this core doesn't break without causing a lot of issues, but I did not see it reported yet. SO, this may be a pipeline plugin problem???? But this is variable assignment. It feels core.

Are you interested in contributing a fix?

No response

[daniel-beck]

This has to be new behavior

Are you reporting a regression? If so, which versions of Jenkins and Pipeline CPS did this last work with?

[cknowlto]

I don't know. This is the first time I am trying to use complex conditional behavior in a pipeline. We were using simple single when statements, but those were not getting the job done right because of how git works. I was asked to re-implement. I spent the first few hours getting frustrated with how when works then I gave up and went to if/then and then discovered that simple variable assignment for env variables was just not working at all. I need these flags to persist across steps, and to be available to shell commands. env should be the right place. This is 100% reproducible on three different jenkins servers USING the code I sent you. Its very possible that _I_ am doing something wrong. ChrisK

…

On Thu, Jan 29, 2026 at 6:57 AM Daniel Beck ***@***.***> wrote: *daniel-beck* left a comment (jenkinsci/pipeline-model-definition-plugin#1496) <#1496 (comment)> This has to be new behavior Are you reporting a regression? If so, which versions of Jenkins and Pipeline CPS did this last work with? — Reply to this email directly, view it on GitHub <#1496 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADIAD74C4DCC3BOSUGINSSD4JHYR3AVCNFSM6AAAAACTHHUI3WVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQMJXGE4TMOJXHA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[daniel-beck]

env is global for the pipeline and not scoped to a block or script. I see nothing wrong "actual results". "whatever"/"different whatever" look like an incorrect assumption.

[cknowlto]

No. Look at the assignments. They don't work. At all. Expected results are that the values of the flags should change as a result of the assignments. They dont

…

On Thu, Jan 29, 2026, 8:31 AM Daniel Beck ***@***.***> wrote: *daniel-beck* left a comment (jenkinsci/pipeline-model-definition-plugin#1496) <#1496 (comment)> env is global for the pipeline and not scoped to a block or script. I see nothing wrong "actual results". "whatever"/"different whatever" look like an incorrect assumption. — Reply to this email directly, view it on GitHub <#1496 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADIAD7ZRAVYKDCFNNGRAISD4JIDTLAVCNFSM6AAAAACTHHUI3WVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQMJXG4YTEOBVHA> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[lemeurherve]

Can you reproduce your expected results from a previous Jenkins release? If so, which one?

[cknowlto]

I don't have any instances of Jenkins I can downgrade. We have three production instances. All running 2.543

…

On Thu, Jan 29, 2026, 9:44 AM Hervé Le Meur ***@***.***> wrote: *lemeurherve* left a comment (jenkinsci/pipeline-model-definition-plugin#1496) <#1496 (comment)> Can you reproduce your expected results from a previous Jenkins release? If so, which one? — Reply to this email directly, view it on GitHub <#1496 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADIAD764YDIY5D542OX7KDD4JIMDZAVCNFSM6AAAAACTHHUI3WVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZTQMJYGEZDCOJZHE> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[daniel-beck]

This appears to be an issue in Pipeline: Declarative. Running the echo statements after the pipeline { } block reveals value updates missing from the script { } blocks inside pipeline { }. I'm transferring this issue over.