After my project was downgraded from unity2019.3.4 to 2018.4.18, the following error occurred when p

After my project was downgraded from unity2019.3.4 to 2018.4.18, the following error occurred when packaging and releasing android. Please help me。
---------------------------
CommandInvokationFailure: Gradle build failed.
C:\Program Files\Unity\Hub\Editor\2018.4.18f1\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\OpenJDK\Windows\bin\java.exe -classpath "C:\Program Files\Unity\Hub\Editor\2018.4.18f1\Editor\Data\PlaybackEngines\AndroidPlayer\Tools\gradle\lib\gradle-launcher-5.1.1.jar" org.gradle.launcher.GradleMain "-Dorg.gradle.jvmargs=-Xmx4096m" "assembleRelease"

stderr[

FAILURE: Build failed with an exception.

* Where:
Build file 'E:\unityPro\fightgrid_2018\New Unity Project\Temp\gradleOut\build.gradle' line: 3

* What went wrong:
A problem occurred evaluating root project 'gradleOut'.
> Plugin with id 'com.android.library' not found.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output. Run with --scan to get full insights.

* Get more help at https://help.gradle.org

BUILD FAILED in 0s
]
stdout[

]
exit code: 1
-------------------------------------------------

 

Thank you I have solved the problem

 

How did you solve it?