runtime.java_no_main_manifest

The jar has no main class

A mevcore app hosting error at the “start / health check” stage.

What it means

The jar the application starts from has no Main-Class: it is a library jar without its dependencies.

The build passed, but the app did not start or did not answer the health check.

Typical causes

The app does not listen on 0.0.0.0 and the port from the PORT variable
An environment variable is missing, or the database or Redis is not connected
The start command is wrong or the process exits right away

How to fix it on mevcore

Build a runnable jar (the Spring Boot plugin, maven-shade-plugin, the Gradle application or shadow plugin) or change the start command in the settings.

1 Open the app in the mevcore panel: the Problems card on the overview shows this error and the log line it was found in.
It is fixed on the “Settings” tab of the app.
2 After the fix, deploy again. If it fails again, the log ends with [mevcore] lines naming the new error code.
3 The "Ask AI" button next to the error prepares a request for ChatGPT or Claude: the error code, the end of the log without secrets and the app settings.

For an AI assistant

The same in English: paste it together with the log into the AI chat.

mevcore error code: runtime.java_no_main_manifest
phase: start / health check
diagnosis: The jar has no main class
platform hint: The jar the application starts from has no Main-Class: it is a library jar without its dependencies. Build a runnable jar (the Spring Boot plugin, maven-shade-plugin, the Gradle application or shadow plugin) or change the start command in the settings.
platform docs: https://mevcore.com/llms-full.txt

Can't fix it?

Message support with the error code: we will tell you what to change in the project or settings.

App hosting