Problem in migration from WAS4 to WAS5.1

I am trying to migrate my application from WAS 4 to WAS5.1, but after a successful build stage, I am facing a problem in the deploy stage.
I get an error log as foolows:-

Buildfile: /var/webeng/build/j2ee/xml/build.xml

init:
[echo] Starting common init

deployEnterpriseApplication:

init:
[echo] Starting init

clrpwds:

deploy:
[echo] Start deploy
[wsadmin] WASX7209I: Connected to process "dmgr" on node DevCell1DM using SOAP connector; The type of process is: DeploymentManager
[wsadmin] Application Name: provider_edi
[wsadmin] Server Name : cl_app201_dev
[wsadmin] Environment : dev
[wsadmin] Directory : /var/webapps/Development

[wsadmin] Properties being used for deployment:
[wsadmin] preCompileJSP == false
[wsadmin] contextroot == default
[wsadmin] "Running deployment with bindings file: false "

[wsadmin] About to Install Application with options:
[wsadmin] Application Name : provider_edi
[wsadmin] Application Deployed Name: provider_edi_dev
[wsadmin] Cluster Name : cl_app201_dev
[wsadmin] With Bindings : false
[wsadmin] Source Directory : /var/webapps/Development/provider_edi/

[wsadmin] Installing application provider_edi to cluster cl_app201_dev
[wsadmin] - Installation type: New Install
[wsadmin] - Not using bindings file
[wsadmin] - PreCompile JSPs : false

[wsadmin] Install options:
[wsadmin] Ear Location: /var/webapps/Development/provider_edi/ear/provider_edi.ear
[wsadmin] Options : -appname provider_edi_dev -cluster cl_app201_dev

[wsadmin] Installation Complete...

[wsadmin] WASX7017E: Exception received while running file "/var/webeng/jacl/deployEntApp.jacl"; exception information: com.ibm.websphere.management.application.client.AppDeploymentException: AppDeploymentException: [ADMA0092E: Unexpected exception occurred while preparing task MapRunAsRolesToUsers. Please check server machines FFDC for more information.]
[wsadmin] AppDeploymentException: []
[wsadmin] com.ibm.etools.archive.exception.DeploymentDescriptorLoadException: WEB-INF/web.xml
[wsadmin] com.ibm.websphere.management.application.client.AppDeploymentException: AppDeploymentException: []
[wsadmin] com.ibm.etools.archive.exception.DeploymentDescriptorLoadException: WEB-INF/web.xml
[wsadmin] com.ibm.etools.archive.exception.DeploymentDescriptorLoadException: com.ibm.etools.archive.exception.DeploymentDescriptorLoadException: WEB-INF/web.xml

BUILD FAILED
/var/webeng/build/j2ee/xml/build.xml:54: Following error occured while executing this line
/var/webeng/build/j2ee/xml/build.entapp.xml:70: Java returned: 105

Total time: 13 seconds
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I am clueless as to where exactly the error is. My web.xml seems fine. Can anyone help me with this? The problem needs to be dealt with very urgently.