required type 'int' for property 'maxConcurrency'; nested exception is java.lang.NumberFormatException - MuleSoft

After updating an app from Mule Runtime 4.4.0 to 4.6.9 an error occurs during deploy on CloudHub. ** when deployed on Studio the app runs without raising an error.

The error on CloudHub:

Your application has failed with exception java.lang.IllegalStateException: 
com.mulesoft.ch.services.agent.muleAgent.MuleAgentException: 
{
"type":"class java.lang.IllegalArgumentException",
"message":"There was an error on the Mule Runtime while deploying the application job-example. 
Error: Failed to deploy artifact [job-example]. 
NumberFormatException: For input string: \"\""}

The error after downloading the log from cloudhub:

2024-12-27 18:24:26.900 INFO    org.mule.runtime.core.internal.construct.FlowConstructLifecycleManager [ArtifactDeployer.start.01]: Starting flow: flow-trigger
2024-12-27 18:24:26.926 ERROR   org.mule.runtime.core.internal.processor.strategy.StreamEmitterProcessingStrategyFactory$StreamEmitterProcessingStrategy [ArtifactDeployer.start.01]: Exception reached PS subscriber for flow 'flow-trigger'
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'subflow01': Cannot create inner bean '(inner bean)#1ff9590d' of type [org.mule.runtime.core.internal.routing.Foreach] while setting bean property 'messageProcessors' with key [1]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#1ff9590d': Cannot create inner bean '(inner bean)#5930f45d' of type [org.mule.runtime.core.internal.routing.Foreach] while setting bean property 'messageProcessors' with key [3]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#5930f45d': Cannot create inner bean '(inner bean)#33016a6c' of type [org.mule.runtime.core.internal.routing.ParallelForEach] while setting bean property 'messageProcessors' with key [0]; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name '(inner bean)#33016a6c': Initialization of bean failed; nested exception is org.springframework.beans.TypeMismatchException: Failed to convert property value of type 'java.lang.String' to required type 'int' for property 'maxConcurrency'; nested exception is java.lang.NumberFormatException: For input string: ""
    at org.springframework.beans.factory.support.BeanDefinitionValueResolver.resolveInnerBean(BeanDefinitionValueResolver.java:389)
    Suppressed: The stacktrace has been enhanced by Reactor, refer to additional information below: 
Error has been observed at the following site(s):
    *__checkpoint ⇢ flow-trigger/processors/3

The XML with a few lines of the implementation related to the error:

                <parallel-foreach
                    maxConcurrency="${scheduler.flowTrigger.parallelForEach.maxConcurrency}"
                    target="hasSecond"
                    targetValue="#[if(not isEmpty(payload.*payload) ) true else false]">
                    <ee:transform>
                        <ee:message>
                        </ee:message>
                        <ee:variables>
                            <ee:set-variable variableName="path"><![CDATA[%dw 2.0
output application/java
---
p('app.path.flowTrigger')]]></ee:set-variable>
                            <ee:set-variable variableName="method"><![CDATA[%dw 2.0
output application/java
---
"DELETE"]]></ee:set-variable>
                            <ee:set-variable variableName="uriParams"><![CDATA[%dw 2.0
output application/java
---
{
    "id"    : payload.id,
}]]></ee:set-variable>
                        </ee:variables>
                    </ee:transform>
                    <until-successful
                        maxRetries="${api.retry}"
                        millisBetweenRetries="${api.retryTime}">
                        <try>
                            <http:request
                                method="#[vars.method]"
                                config-ref="HTTP_Request_configuration_01"
                                path="#[vars.path]"
                                responseTimeout="${app.responseTimeout}"
                                sendBodyMode="NEVER">
                                <http:uri-params><![CDATA[#[vars.uriParams default {}]]]></http:uri-params>
                                <http:response-validator>
                                    <http:success-status-code-validator values="${app.successResponseCode}"/>
                                </http:response-validator>
                            </http:request>
                        </try>
                    </until-successful>
                </parallel-foreach>

The YAML config file:

api:
  retry: "3"
  retryTime: "5000" #Miliseconds

app:
  path:
    flowTrigger: "/api/v1/something"
  responseTimeout: "120000"
  successResponseCode: "200,201,400,401,404,500"

scheduler:
  flowTrigger:
    parallelForEach.maxConcurrency: ""

I need to understand the error and fix the issue.