Eclipse Oxygen - The project was not built since its build path is incomplete

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I just installed Eclipse Oxygen and tried to open an existing project into the workbench but I get this error:

The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project

I tried right clicking on the project - went to Properties - Java Build Path - Libraries - Add Library - JRE System Library and selected Workbench default JRE (jre1.8.0_60).

I then cleaned and rebuilt the project but it then causes more errors to come up like:

ActionBar cannot be resolved to a type
Activity cannot be resolved to a variable
AdapterView cannot be resolved to a type
ArrayAdapter cannot be resolved to a type

Are you using Maven? If so,

  1. Right-click on the project, Build Path and go to Configure Build Path
  2. Click the libraries tab. If Maven dependencies are not in the list, you need to add it.
  3. Close the dialog.

To add it: Right-click on the project, Maven → Disable Maven Nature Right-click on the project, Configure → Convert to Maven Project.

And then clean

Edit 1:

If that doesn't resolve the issue try right-clicking on your project and select properties. Select Java Build Path → Library tab. Look for a JVM. If it's not there, click to add Library and add the default JVM. If VM is there, click edit and select the default JVM. Hopefully, that works.

Edit 2:

You can also try going into the folder where you have all your projects and delete the .metadata for eclipse (be aware that you'll have to re-import all the projects afterwards! Also all the environment settings you've set would also have to be redone). After it was deleted just import the project again, and hopefully, it works.

Eclipse Oxygen, The project was not built since its build path is incomplete. let readers know whether or not you are transferring code from Oxygen to Photon. The project was not built since its build path is incomplete. Cannot find the class file for org.eclipse.emf.common.util.EList. Fix the build path then try building this project. Type-The type org.eclipse.emf.common.util.EList cannot be resolved. It is indirectly referenced from required .class files. Tried to fix the issue by performing actions:

Here is what made the error disappear for me:

Close eclipse, go to the terminal and run:

$ mvn clean eclipse:clean eclipse:eclipse

Eclipse Community Forums: Newcomers » The project was not built , Eclipse build error: The project was not built since its build path is incomplete. Cannot find the class file for xxxxx. Fix the build path then try  Right CLick on your project, Choose Build Path > Configure Build Path; Select Libraries Tab and delete any arbitrary library or anything else causing errors in Build Path. Click on Add Library button, Select JRE System Library and click Next. Choose last Radiobutton option Workspace default JRE and click Finish. Clean and build your project.

I'm also using Eclipse Oxygen, migrated from Mars. I faced the same error. I deleted .metadata, .recommenders folders and added projects from archive and issue is solved. I also use Android Studio but i like Eclipse much more.

Eclipse build error: The project was not built since its build path is , The project was not built since its build path is incomplete. Cannot find the class file for javax.servlet.http.HttpServletResponse. Fix the build  I recently copied a good, working project to a different workspace, did a "File > Import" to import it in its new workspace, but after doing a Clean and Build, got the "The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object.

At my system the Java Runtime JAR file jrt-fs.jar was not found because it was in the wrong directory. This file should be located in the "lib" subfolder. If you installed Java at "C:\Temp\java" the file should be here at C:\Temp\java\lib\jrt-fs.jar .

These are the steps to make jrt-fs.jar available to Eclipse:

  1. Window / Preferences -> the "Preferences" Window opens
  2. Select in the left menu: Java / Installed JREs
  3. Press the [Add...] Button -> A window opens
  4. Select "Standard VM" - The window "JRE Definition" opens.
  5. Enter your path information:
  6. JRE home = "C:\Temp\java"
  7. JRE name = "MyJRE"
  8. Select [Add External JARs...] to link the jrt-fs.jar
  9. JRE system libaries: "C:\Temp\java\lib\jrt-fs.jar"

It worked for me with OpenJDK12 and Eclipse 2019-09 (4.13.0). Eclipse reported me this error:

The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project

"project was not built since its build path is incomple, "The project was not built since its build path is incomplete. Cannot find the class file for org.eclipse.hyades.edit.datapool.IDatapoolRecord. Eclipse error: The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this project

I had faced this problem. I added the C:\Users\Office 2\android-sdks\platforms\android-19\android.jar to the Java Build Path's Library. And the project started to run again. The problem occurred due to my carelessness. Yesterday night I was updating the Android SDK, and at the same time I tried to run the project, while the SDK Manager was uncompressing the system image. The Project couldn't start and the error occurred.

I tried all the methods given by others. But nothing worked. It solved when I added the android.jar to the library.

I guessed it that android library is missing. not the Java, when I saw the errors only at the android methods and imports. But when I read the posts, I got confused and wasted some time trying wrong way.

Importing a package from RFT script results in "The project was not , The project was not built since its build path is incomplete. Cannot find the class file for java.lang.Object. Fix the build path then try building this  When importing ONOS into Eclipse Luna I got this error:" The project was not built since its build path is incomplete. Cannot find the class file for org.osgi.framework.ServiceReference. Fix the build path then try building this project The type org.osgi.framework.ServiceReference cannot be resolved. It is indirectly referenced from required

Eclipse build errors - java , I am using new Eclipse Oxygen. My project setup includes Maven. One of the Maven dependencies is Guava: <dependency>  For the Love of Physics - Walter Lewin - May 16, 2011 - Duration: 1:01:26. Lectures by Walter Lewin. They will make you ♥ Physics. Recommended for you

Eclipse: The project was not built since its build path is incomplete , 1º Problem , after import the grandle project to eclipse oxigen my first error was "​The project was not built since its build path is incomplete. When your Java project requires JAR libraries (Java Archive) to function, you have to configure your project to include the libraries in its build path. Fortunately, Eclipse makes this process simple and easy to remember. The build used here is Eclipse Java - Ganymede 3.4.0.

Problems running libgdx with Eclipse Oxygen, Eclipse Oxygen - The project was not built since its build path is incomplete. Multi tool use. up vote 2 down vote favorite. I just installed Eclipse Oxygen and tried 

Comments
  • Could you switch to Android Studio instead ? Because Eclipse is deprecated now.
  • No I am not using Maven. I already tried adding a JVM which a said in my question. When I do that it causes more errors
  • You can also try going into the folder where you have all your projects and delete the .metadata for Eclipse (be aware that you'll have to re-import all the projects afterwards! Also all the environment settings you've set would also have to be redone). After it was deleted just import the project again, and hopefully it works.
  • At least for me this did not work.
  • Eclipse for Android is not supported now. You can't use Api 26+ and support libraries and some other stuff like MVVM, Room, etc. You should migrate to Android Studio. I resisted that for awhile but it became impossible to work without new libraries. You can use AS like Eclipse with workspace if you add projects as modules. I Keep 10+ separate projects in one project using modules and it gets quite easy to check out if i need some snippets from another project.