Project referenced by the classpath does not exist

The project: <project name> which is referenced by the classpath, does not exist. error in Eclipse

Resolution

Right click on the project from project explorer >> select build path >> configure build path >> a popup window will appear. Go to project tab and check the entry of project if that project is not in your eclipse project explorer then remove the project and apply the changes. 

Now build the project again.

No Java virtual machine was found

Error: A Java runtime environment (JRE) or Java Development Kit (JDK) must be available in order to run Eclipse. No Java virtual machine was found after searching the following locations: C:\Program Files\Java\jre1.8.0_221\bin

Cause of error: when we update the Java version, or install a new version of Java in machine.

Solution: We need to manually update path of current JRE or JDK path in Eclipse setting file.

Where I can find the Eclipse setting file?

Directory: C:\Users\rashidjorvee\eclipse\jee-2019-06\eclipse\eclipse.ini
Below is the sample of eclipse.ini file. You may open this file using notepad and notepad++.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

-startup plugins/org.eclipse.equinox.launcher_1.5.400.v20190515-0925.jar --launcher.library C:\Users\username\.p2\pool\plugins\org.eclipse.equinox.launcher.win32.win32.x86_64_1.1.1000.v2019882098-2010 -product org.eclipse.epp.package.jee.product -showsplash org.eclipse.epp.package.common --launcher.defaultAction openFile --launcher.appendVmargs -vm C:/Program Files/Java/jre1.8.0_221/bin -vmargs -Dosgi.requiredJavaVersion=1.8 -Dosgi.instance.area.default=@user.home/eclipse-workspace -XX:+UseG1GC -XX:+UseStringDeduplication --add-modules=ALL-SYSTEM -Dosgi.requiredJavaVersion=1.8 -Dosgi.dataAreaRequiresExplicitInit=true -Xms256m -Xmx1024m --add-modules=ALL-SYSTEM -Declipse.p2.max.threads=10 -Doomph.update.url=http://download.eclipse.org/oomph/updates/milestone/latest -Doomph.redirection.index.redirection=index:/->http://git.eclipse.org/c/oomph/org.eclipse.oomph.git/plain/setups/

In eclipse.ini file please update the correct JRE or JDK path at line number 13 under the -vm (virtual machine) and then save the file.

This will fix your issue and you will be now able to open the eclipse IDE without any issue.

Where to find the installed JDK and JRE in machine?

In windows inside the profile files >> Java, you will find the installed JRE and JDK.

e.g. path of a JDK version 1.8 : C:\Program Files\Java\jdk1.8.0_221\bin