Jenkins error while analyzing sonar scanner - jenkins

Question

i'm getting the above error eventhoug it has all the properties. all the sonar properties defined in -Dsettings=./sonar-project.properties file. still getting the same error.
[Pipeline] }
[Pipeline] // stage
[Pipeline] stage
[Pipeline] { (sonarqube analysis)
[Pipeline] withSonarQubeEnv Injecting SonarQube environment variables using the configuration: sonar
[Pipeline] {
[Pipeline] sh
+ /var/jenkins_home/tools/hudson.plugins.sonar.SonarRunnerInstallation/sonar/bin/sonar-scanner -
Dproject.settings=./sonar-project.properties
INFO: Scanner configuration file:
/var/jenkins_home/tools/hudson.plugins.sonar.SonarRunnerInstallation/sonar/conf/sonar-
scanner.properties
INFO: Project root configuration file: NONE
INFO: SonarScanner 4.6.2.2472
INFO: Java 1.8.0_292 AdoptOpenJDK (64-bit)
INFO: Linux 3.10.0-1160.24.1.el7.x86_64 amd64
INFO: User cache: /var/jenkins_home/.sonar/cache
INFO: Scanner configuration file:
/var/jenkins_home/tools/hudson.plugins.sonar.SonarRunnerInstallation/sonar/conf/sonar-
scanner.properties
INFO: Project root configuration file: NONE
INFO: Analyzing on SonarQube server 7.5.0
INFO: Default locale: "en_US", source code encoding: "UTF-8" (analysis is platform dependent)
INFO: Publish mode
INFO: Load global settings
INFO: Load global settings (done) | time=122ms
INFO: Server id: BF41A1F2-AXjqWPPbWWxxqvtkaXSc
INFO: User cache: /var/jenkins_home/.sonar/cache
INFO: Load/download plugins
INFO: Load plugins index
INFO: Load plugins index (done) | time=60ms
INFO: Load/download plugins (done) | time=1203ms
INFO: Loaded core extensions:
INFO: Process project properties
INFO: ------------------------------------------------------------------------
INFO: EXECUTION FAILURE
INFO: ------------------------------------------------------------------------
INFO: Total time: 4.114s
INFO: Final Memory: 11M/219M
INFO: ------------------------------------------------------------------------
ERROR: Error during SonarScanner execution
ERROR: You must define the following mandatory properties for 'Unknown': sonar.projectKey,
sonar.sources
ERROR:
ERROR: Re-run SonarScanner using the -X switch to enable full debug logging.
[Pipeline] }
WARN: Unable to locate 'report-task.txt' in the workspace. Did the 'SonarScanner' succeed?
[Pipeline] // 'withSonarQubeEnv'
[Pipeline] }
[Pipeline] // stage
[Pipeline] }
[Pipeline] // 'withEnv'
[Pipeline] }
[Pipeline] // 'withEnv'
[Pipeline] }
[Pipeline] // node
[Pipeline] End of Pipeline
ERROR: script returned exit code 2
Finished: FAILURE
Shell Script -- ${scannerHome}/bin/sonar-scanner -Dproject.settings=./sonar-project.properties (self time 2s)
/var/jenkins_home/tools/hudson.plugins.sonar.SonarRunnerInstallation/sonar/bin/sonar-scanner -Dproject.settings=./sonar-project.properties
INFO: Scanner configuration file: /var/jenkins_home/tools/hudson.plugins.sonar.SonarRunnerInstallation/sonar/conf/sonar-scanner.properties
INFO: Project root configuration file: NONE
INFO: SonarScanner 4.6.2.2472
INFO: Java 1.8.0_292 AdoptOpenJDK (64-bit)
INFO: Linux 3.10.0-1160.24.1.el7.x86_64 amd64
INFO: User cache: /var/jenkins_home/.sonar/cache
INFO: Scanner configuration file: /var/jenkins_home/tools/hudson.plugins.sonar.SonarRunnerInstallation/sonar/conf/sonar-scanner.properties
INFO: Project root configuration file: NONE
INFO: Analyzing on SonarQube server 8.9.0
INFO: Default locale: "en_US", source code encoding: "UTF-8" (analysis is platform dependent)
WARN: SonarScanner will require Java 11 to run, starting in SonarQube 9.x
INFO: Load global settings
INFO: Load global settings (done) | time=90ms
INFO: Server id: BF41A1F2-AXl0u-SQAyVEzukSwxVv
INFO: User cache: /var/jenkins_home/.sonar/cache
INFO: Load/download plugins
INFO: Load plugins index
INFO: Load plugins index (done) | time=51ms
INFO: Load/download plugins (done) | time=92ms
INFO: Process project properties
INFO: ------------------------------------------------------------------------
INFO: EXECUTION FAILURE
INFO: ------------------------------------------------------------------------
INFO: Total time: 1.837s
INFO: Final Memory: 9M/125M
INFO: ------------------------------------------------------------------------
ERROR: Error during SonarScanner execution
ERROR: You must define the following mandatory properties for 'Unknown': sonar.projectKey
ERROR:
ERROR: Re-run SonarScanner using the -X switch to enable full debug logging.