@Marvin - I am seeing the following error sometimes in my unit tests:

RuntimeError: Timed out while attempting to connect to ephemeral Prefect API server.

. This is using the test harness like so:

with prefect_test_harness(server_startup_timeout=60)

The error you're encountering,

RuntimeError: Timed out while attempting to connect to ephemeral Prefect API server

, is a known issue that can occur during unit tests using the

prefect_test_harness

. This issue seems to be more prevalent when using Prefect 3.1.5 and can be exacerbated by certain CI configurations, such as the use of

pytest-xdist

. Here are some insights and potential solutions: 1. SQL Syntax Error: There was a reported issue where SQL queries in the test harness could fail due to incorrect use of double quotes instead of single quotes. This can cause the ephemeral server to hang. Ensure that any SQL queries used are syntactically correct with proper quoting. 2. Server Startup Timeout: The default timeout for the ephemeral server startup is 10 seconds, which might be insufficient in some environments. You can increase this timeout by setting the environment variable

PREFECT_SERVER_EPHEMERAL_STARTUP_TIMEOUT_SECONDS

to a higher value. For example, you might want to try increasing it beyond the default 20 seconds to see if it resolves the issue. 3. CI Environment: The issue is often observed in CI environments and might be related to resource constraints or parallel test execution. If you're using

pytest-xdist

, consider reducing the number of parallel processes or running the tests sequentially to determine if this mitigates the problem. 4. Review and Update: Check if there are any updates or patches available for the version of Prefect you are using. Sometimes, upgrading to a newer version can resolve such issues. For more detailed guidance, you can refer to the following resources: - Prefect Settings Reference - GitHub Issue Discussion If the problem persists, you might want to engage with the Prefect community or consider filing a new issue with detailed logs and configurations.