Error: Could not find or load main class add configuration IntelliJ and class undefined in IntelliJ

The "Could not find or load main class" error occurs when the JVM fails to load the main class. This can happen due to various reasons, such as: The class being declared in the incorrect package. The file path of the class not matching the fully qualified name.
In spring boot and maven based plugins, we solve the problem as shown in this video.

[danielasegadilha]

I'm looking for this for days man, thank u so much

[ajay-rr]

In my intellij ide its showing module name adjacent to folder name in square brackets....but in yours it isn't...on the left below Project where it's mentioned mailer-app F:\projects\mailer-app do i need do anything or is it alright??? plz tell

[botsynth]

interesting! but I resolved by: clean by maven, compile by maven - and problem had gone.

[mouadfifel]

At the end, I know how to fix this, thanks !

[cakranurhidayah]

Good jobb bro thankyou very much you saved me.

[ayael]

i have this err
Error occurred during initialization of boot layer
Module com.example.javafxprojet not found

Process finished with exit code 1
any idea??

[knn]

why didnt i find this video, before i deleted my project and restarted it .

[lamaalsharyan]

No words tell you how I am thankful to you! 🤍♥