java error in eclipse "The project was not built due to.."

Question

i installed java and eclipse, but i keep getting this error.
(environment variables changed ,java -version / javac -version checked from cmd)
after that what i did is:
changing java version from 10 to 15(reinstall)
reinstall eclipse several times

what should i do next?

eclipse: Eclipse IDE 2020‑09
java: jdk-13.0.2_windows-x64

** The project was not built due to "Failed to init ct.sym for C:\Users\mirei\AppData\Local\Temp\eoiE4ED.tmp\plugins\org.eclipse.justj.openjdk.hotspot.jre.minimal.stripped.win32.x86_64_14.0.2.v20200815-0932\jre\lib\jrt-fs.jar". Fix the problem, then try refreshing this project and building it since it may be inconsistent **

Answer 1

Please open the project properties: >> right-click on that project. >> Last option for Properties >> choose Java Compiler section, >> in the Use '--release' option box, uncheck that box. Select Apply and Yes to rebuild the project.