We use pipeline jobs retrieved via Git SCM. There are simplified version of how they look like:

// name: my_upstream_job.groovy
// just triggers some downstream build

thebuild = build job: 'my_downstream_job',
            propagate: false,
            parameters: [
                string(name: "my_str_param", value: "foo")
            ]
           

// name: my_downstream_job.groovy
// occasionally fails due to java.lang.NullPointerException: Cannot invoke method contains() on null object

properties([
    parameters([
        string(
            defaultValue: '',
            description: 'Some parameter for demo',
            name: 'my_str_param')
    ])
])

// if we're using something like this outside of node() step
// build can occasionally fail
if (env.my_str_param.contains("foo")) {
    println 'Called from upstream build'
}

// other steps
node {
    println "Building and testing"
}

Sometimes Jenkins can 'lose' parameters passed from upstream build in my configuration. About 1 time per 5 successful executions downstream build will fail with an error like this:

java.lang.NullPointerException: Cannot invoke method contains() on null object 

However, in build.xml file for that build on Jenkins master all parameters' values  are in place, and I can click 'Rebuild' and build will pass. But 'Parameters' page for the failed build is empty.

In Jenkins log there are many entries like this:

Skipped parameter `param_name` as it is undefined on `job_name`. Set `-Dhudson.model.ParametersAction.keepUndefinedParameters=true` to allow undefined parameters to be injected as environment variables or `-Dhudson.model.ParametersAction.safeParameters=[comma-separated list]` to whitelist specific parameter names, even though it represents a security breach or `-Dhudson.model.ParametersAction.keepUndefinedParameters=false` to no longer show this message.

We've "fixed" this by replacing env.param_name with params.param_name in our pipelines and shared library, but env approach used to work before (I can't be really sure whether upgrade broke it or we somehow).

Is there's a way I can investigate further? Please let me know if you need additional information.