Based on the research, I can help explain what's happening and how to fix it. The error you're seeing suggests there might be a configuration issue. Here's what you need to know: 1. In Prefect 3.x, the setting has been updated to use a different name. Instead of

PREFECT_SERVER_ALLOW_EPHEMERAL_MODE

, you should use: -

server.ephemeral.enabled

in your TOML configuration - Or the environment variable

PREFECT_SERVER_EPHEMERAL_ENABLED

To fix this, you have a few options: 1. Option 1: Update your configuration in `prefect.toml`:

toml
   [server.ephemeral]
   enabled = true  # or false depending on your needs

2. Option 2: Set the environment variable:

bash
   export PREFECT_SERVER_EPHEMERAL_ENABLED=true  # or false

3. Option 3: Use the Prefect CLI to set the configuration:

bash
   prefect config set server.ephemeral.enabled=true  # or false

The error occurs because the old configuration key (

PREFECT_SERVER_ALLOW_EPHEMERAL_MODE

) is no longer recognized in newer versions of Prefect. This is part of Prefect's ongoing efforts to standardize configuration settings. Would you like me to help you verify which version of Prefect you're running? That could help us ensure you're using the most appropriate configuration settings for your specific version.

Based on the research and my knowledge of Prefect 2.x, here's what's happening and how to fix it: 1. First, let's verify your Prefect server configuration. When you run

prefect server start

, you need to ensure you have a proper configuration set up. Try these steps: 2. Clear your existing configuration:

bash
   prefect config unset PREFECT_SERVER_ALLOW_EPHEMERAL_MODE

3. Then, set up your server configuration properly:

bash
   prefect config set PREFECT_API_URL="<http://127.0.0.1:4200/api>"

4. Start the Prefect server:

bash
   prefect server start

If you're still getting the error, there might be a conflict in your configuration files. You can check your configuration locations with:

bash
prefect config view

Also, make sure you don't have any conflicting settings in: - Environment variables -

~/.prefect/config.toml

- Local

prefect.toml

files The error you're seeing suggests that there might be a configuration setting that's not compatible with your version. In Prefect 2.x, the server typically doesn't need explicit ephemeral mode configuration - it's handled automatically. Would you like me to help you check your current configuration setup? Also, while we're at it, I should mention that Prefect 2.x is approaching end-of-life, and you might want to consider upgrading to Prefect 3.x in the future, which has improved server handling and configuration options.