Getting error when executing the selenium tests in jenkins. How to resolve this issue? Also note that jenkins is running in linux environment

I am trying to run the selenium tests in linux (cent7.6 os) environment using the jenkins job. But showing errors. Below is the jenkins job output showing some errors.

-------------------------------------------------------
 T E S T S
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Running TestSuite
Failed to open connection to "session" message bus: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
1597566987656   mozrunner::runner   INFO    Running command: "/bin/firefox" "-marionette" "--display=9999" "-foreground" "-no-remote" "-profile" "/tmp/rust_mozprofile7DbCyH"
Failed to open connection to "session" message bus: Unable to autolaunch a dbus-daemon without a $DISPLAY for X11
Running without a11y support!
Error: cannot open display: 9999
Tests run: 1, Failures: 1, Errors: 0, Skipped: 0, Time elapsed: 1.03 sec <<< FAILURE!

Results :

Failed tests:   loginTest4(com.training.browsers.LinuxTest): invalid argument: can't kill an exited process

Tests run: 1, Failures: 1, Errors: 0, Skipped: 0

[ERROR] There are test failures.

Please refer to /var/lib/jenkins/workspace/SampleProject/target/surefire-reports for the individual test results.
[JENKINS] Recording test results
[INFO] [1m------------------------------------------------------------------------[m
[INFO] [1;32mBUILD SUCCESS[m
[INFO] [1m------------------------------------------------------------------------[m
[INFO] Total time: 5.205 s
[INFO] Finished at: 2020-08-16T14:06:29+05:30
[INFO] [1m------------------------------------------------------------------------[m
Waiting for Jenkins to finish collecting data
[JENKINS] Archiving /var/lib/jenkins/workspace/SampleProject/pom.xml to MultiBrowserTesting/MultiBrowserTesting/0.0.1-SNAPSHOT/MultiBrowserTesting-0.0.1-SNAPSHOT.pom
An attempt to send an e-mail to empty list of recipients, ignored.
channel stopped
An attempt to send an e-mail to empty list of recipients, ignored.
Finished: UNSTABLE