Based on the research and GitHub issues, I can identify the likely cause of your 404 error. There are a couple of important points to note: 1. Name Format Requirement: When using

read_deployment_by_name

, you need to provide the name in the format

{flow_name}/{deployment_name}

. You appear to be only providing the deployment name. 2. Flow Name Transformation: There's an important caveat (documented in issue #15571) - Prefect automatically converts underscores (

_

) in flow names to hyphens (

-

) when creating deployments. This can cause confusion when trying to reference the deployment later. To fix this, you should: 1. First, verify your flow and deployment names by listing all deployments:

python
deployments = await client.read_deployments()
for d in deployments:
    print(f"Flow name: {d.flow_name}, Deployment name: {d.name}")

2. Then use the correct format to read the deployment:

python
# If your flow is named "my_flow" and deployment is "my-deployment"
# You would need to use:
await client.read_deployment_by_name("my-flow/my-deployment")  # Note the hyphen in flow name

The 404 error you're seeing suggests that either: - You're not providing the flow name part of the path - The flow name you're using has underscores instead of hyphens - The deployment name doesn't exactly match what's stored in the system If you're still having trouble, could you share: 1. The output of

read_deployments()

2. The exact flow name from your flow definition 3. The exact deployment name you're trying to access This will help me provide more specific guidance for your case.

You're absolutely right - the current "Not Found" error message is not helpful enough for debugging API key issues. A more informative error message should indicate: 1. That there might be an authentication issue 2. Which account/workspace combination was attempted 3. A hint to check the API key validity This would help users quickly identify whether they're dealing with: - An incorrect API key - A key that's valid but for the wrong workspace - A key that's valid but for the wrong account - An actual "not found" resource issue Would you mind if I created a GitHub issue to suggest improving this error message? It would help other users avoid similar confusion in the future. The error message could be something like:

Unable to access resource at {url}. Please verify:
- Your API key has access to account {account_id}
- Your API key has access to workspace {workspace_id}
- The resource actually exists at this location

This would make it much clearer that the 404 could be due to authentication issues rather than just a missing resource.

I'll create a detailed issue that could serve as a foundation for a PR. Here's what I'm thinking: 1. Issue Title: "Improve API authentication error messages for better debugging experience" 2. Description:

markdown
### Current Behavior
When making API calls with invalid credentials, users receive a generic 404 Not Found error:
```Client error '404 Not Found' for url '<https://api.prefect.cloud/api/accounts/<account_id>/workspaces/<workspace_id>/deployments/filter>'
Response: {'detail': 'Not Found'}

This makes it difficult to distinguish between: - Invalid API keys - Valid keys with wrong permissions - Valid keys targeting wrong account/workspace - Actually missing resources ### Proposed Solution Enhance error messages to provide more context about authentication failures: 1. For 404s on authenticated endpoints, check if the API key: - Is valid - Has access to the specified account - Has access to the specified workspace 2. Return more descriptive error messages:

python
if not valid_api_key:
    raise PrefectHTTPStatusError(
        "Authentication failed. Please verify your API key is valid and not expired.",
        status_code=401  # More appropriate than 404 for auth failures
    )
elif not has_account_access:
    raise PrefectHTTPStatusError(
        f"Your API key does not have access to account {account_id}. "
        f"Please verify you're using the correct key for this account.",
        status_code=403
    )
# etc.

### Implementation Notes - This would require modifications to the

PrefectHTTPStatusError

handling in the client - We should consider adding a new

PrefectAuthenticationError

class for clearer error hierarchies - The error messages should be consistent across all authenticated endpoints ### Benefits - Faster debugging of authentication issues - Clearer distinction between auth failures and missing resources - Better developer experience, especially for new users ### Potential Implementation Path 1. Add authentication status checking to the client 2. Create new error types if needed 3. Modify error handling to include context-aware messages 4. Add tests for various authentication failure scenarios Would you like me to proceed with a PR implementing these changes? ``` 3. Labels:

enhancement

,

good first issue

,

documentation

If you'd like, I could create this issue now and then work on a PR that implements these changes. The PR would focus on: 1. Adding proper authentication status checking 2. Creating more specific error types 3. Implementing context-aware error messages 4. Adding comprehensive tests Would you like me to create the issue now? Also, would you prefer I create it as a standalone issue first, or would you rather I submit it directly with an implementation PR? Note: While I'm just an AI and can't directly create GitHub issues or PRs, I can provide the exact content and structure that you or someone else could use to create them.