Class not found in module warning when try to create Run/Debug Configuration in Intellij

Question

Trying to create a Run configuration in Intellij For a Java application and get a warning that Class not found in module and it doesn't create the Run configuration. This only happened once I added the project to BitBucket. Before that it ran fine.

Dagnah

Please check https://mcmap.net/q/390230/-java-lang-classnotfoundexception-when-running-in-intellij-idea. – Marquet

Answer 1

The way I fixed the problem was to remove the existing Content Root from the project and adding a new one. For some reason, it looks like it got corrupted.

File->Project Structure under Modules : then on the far right side of the screen where it says Add Content Root, remove the existing Content Root and add it back again pointing to the correct location.

Dagnah

This happened to me while importing a scala maven project, and intellij was dumb to not recognise the App class. – Souvenir

This was still a working solution for me on IntelliJ IDEA 2020. I suspect this happened to my run configs after an IntelliJ minor version update. – Ettaettari

Tks, after deleting .idea from my git repo, the project stopped compilling (of course...), by setting the 'Sources folder' under Modules, it worked again – Preferable

Answer 2

None of the above worked, I had to do:

File -> Invalidate Caches/ Restart

Upon restart it re-indexed all files and everything worked again as expected.

Maccaboy

Thanks. It works for Rider debugging nodejs application too. – Merridie

Thanks, now i cannot run the app – Furring

Answer 3

I'll explain a little bit more detailed version of the Accepted answer.

1. Open Project structure window (Using Ctrl+Shift+Alt+S shortkey or From File -> Project structure option in the IDE menu)

2. From there, select modules tab and remove the current configuration you have.

3. Import module again.

4. Select the root of your module (The old .iml file should be in that folder)

5. A dialog will popup. Select default options and finish.

6. Apply the modifications by clicking OK.

Brezin

Answer 4

I've struggled with the same problem on my Kotlin project. The solution that works for me:

1. Right mouse click on src/main/kotlin/Main.kt
2. "Override file type"
3. Choose "Kotlin" file type in the "Override file type" menu
4. In the "Run/Debug Configuration" set "Main Class" as "MainKt"

Torrence

Thank you! I had the same problem. I created a new Kotlin project from the Kotlin/Gradle template and added my own main.kt file (called as such) but until I did what you suggested above, got the same error about not being able to find the class in my own module. – Fury

This is the best answer that solved my issue direct, no frills. – Williemaewillies

Answer 5

My variant: Run -> Edit Configurations -> Configuration -> Environment -> Shorten Command Line Select "JAR Manifest".

Dasya

Answer 6

i deleted .iml file and reimported the project using maven.

Venetian

Answer 7

i solved it by right clicking on "pom.xml" -> add as maven project

Flour

Thanks, in version 2023.1 this options moved to "pom.xml" (right click) -> Maven -> Reload project. And it works! – Palmirapalmistry

Answer 8

set working directory to module root directory or $MODULE_WORKING_DIR$ in Run/Debug configurations settings to help Intellij to find classes.

Nonsuch

Answer 9

i had this issue and i found out that the play button on the left side the function is the answer and it solved the error:))

Repurchase

It doesn't work that way - if you have multiple files, you don't know what you're running – Dicrotic