Eclipse, mvn eclipse:clean eclipse:eclipse, Error: Could not find or load main class

Question

Problem : Error: Could not find or load main class

Situation :

1. Spring Boot Project
2. Latest Version of Eclipse, Maven 3.3.1, JDK 1.8.0.242
3. Windows 10
4. Eclipse Build 2019-12

How to reporduce

1. Go to parent of my project
2. Run mvn eclipse:clean eclipse:eclipse
3. Import the projects as Existing projects in workspace ( I do not want to use Maven Project )
4. Go to my main class
5. Right Click Run -> Run As -> Check the Main Class its correct
6. Error: Could not find or load main class

Already tried :

1. Many times clean run mvn clean install mvn eclipse:clean eclipse:eclipse
2. Delete .meta and recreate workspace many times
3. Went to Run as -> Classpath -> Advance -> Add Folder -> Add target/classes
4. Since I am writing this question, I apparently tried everything on StackOverflow related to this issue.

I appreciate if someone can recommend something new .

[ Update ]

The problem is resolved for all the builds other than 2019-12. I have verified for the following

• Eclipse 2019-09 (4.13)
• Eclipse 2019-06 (4.12)
• Eclipse 2019-03 (4.11)

Answer 1

This question convinced me. This only happen 2019-12.
I have verified for the following.

• Spring suite 3
• Spring suite 4
• Eclipse Photon

The cause of the problem is due to restrictions on classpaths that are limited by OS.
- This is a one of related with this issue Java: Support for long classpath on Windows.

You can solve the problem by setting the options for the classpath as shown below.(or from here ) In Spring Tool Suite 3,4 it works without any special configuration.

I haven't found a way to visually identify the problem yet.

This problem is unique.
There's nothing wrong with builds or deploys, it's only a problem when debugging.
So it's easy to tell if it's a problem with the classpath or not.