runtime.port_in_use
Port is already in use
A mevcore app hosting error at the “start / health check” stage.
What it means
The application tries to open a port that is taken.
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
Listen only on the port from the PORT variable.
- 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.
- 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.port_in_use phase: start / health check diagnosis: Port is already in use platform hint: The application tries to open a port that is taken. Listen only on the port from the PORT variable. platform docs: https://mevcore.com/llms-full.txt
Related errors
All error codes · How to prepare your project for mevcore · 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.