java.lang.ClassNotFoundException: scala.meta.metals.Main

[tym-network]

Describe the bug

Metals server crashes when opening a Scala project.

To Reproduce
Steps to reproduce the behavior:

1. Open a Scala project in VSCode
2. In the Notification drawer, it says "Starting Metals server..."
3. After a few seconds, the following error in displayed in the notification server: "The Metals server crashed 5 times in the last 3 minutes. The server will not be restarted."

Expected behavior

The Metals server starts properly.

Screenshots

Installation:

• Operating system: Windows 10
• VSCode version: 1.47.2
• VSCode extension version: 1.9.2
• Metals version: 0.9.2

Additional context

Here is the content of the log file located in AppData/Roaming/Code/logs/xxx/exthost1/output_logging_xxx:

Java home: C:\Program Files\Java\jdk-11.0.8
Error: Could not find or load main class scala.meta.metals.Main
Caused by: java.lang.ClassNotFoundException: scala.meta.metals.Main
[Info  - 22:51:16] Connection to server got closed. Server will restart.
Error: Could not find or load main class scala.meta.metals.Main
Caused by: java.lang.ClassNotFoundException: scala.meta.metals.Main
[Info  - 22:51:17] Connection to server got closed. Server will restart.
Error: Could not find or load main class scala.meta.metals.Main
Caused by: java.lang.ClassNotFoundException: scala.meta.metals.Main
[Info  - 22:51:17] Connection to server got closed. Server will restart.
Error: Could not find or load main class scala.meta.metals.Main
Caused by: java.lang.ClassNotFoundException: scala.meta.metals.Main
[Info  - 22:51:17] Connection to server got closed. Server will restart.
Error: Could not find or load main class scala.meta.metals.Main
Caused by: java.lang.ClassNotFoundException: scala.meta.metals.Main
[Error - 22:51:17] Connection to server got closed. Server will not be restarted.

I installed Java 11 and specified the path in VSCode settings metals.javaHome.
I also installed Scala using the .exe

Could the error be because I have an accent in my first name (which is also in the name of my home folder)?

Search terms
metals server crashed ClassNotFoundException main

[tgodzik]

Thanks for reporting! The issue might be coming from having the additional accent, though I hoped this was fixed recently. Especially that it seems to be running Java properly. I will try to reproduce it locally.

Did you try reloading the window maybe? I've seen situation where the Main class of the server was not detected at first, however I have no idea why.

[tym-network]

Thanks for your blazing fast answer!

Unfortunately, I have the error every time I open VSCode... I've never been able to make it work. Reloading the window or re-opening VSCode doesn't solve the issue.

[tgodzik]

Ok, I can reproduce the issue on Windows. It doesn't seem to cope well with accents.

[vikas-saxena02]

Hi guys, I am getting the same error on Metals 1.2, can you please elaborate on how to bypass it. I do not have accents in username on my system which is RHEL 7.9 running VScode 1.85.2

[divijan]

@vikas-saxena02 any luck with your problem? I'm having the same thing on Windows 10 with cyrillic username

[vikas-saxena02]

@divijan Metals does require a lot of dependencies available to it in order to start which need to come from either mavencentral or if you are in a an airgap system like me from your local package repository such as artificatory or Nexus.
If its the later, you will need to go to settings -> Metals and point the following properties to your repository.

• Coursier Mirror
• Custom Repositories