As of FME Flow 2025.1, the V3 REST API has been deprecated. The current API will remain accessible, but no new features or general bug fixes will be implemented. Starting with FME Flow 2026.1, the V3 API will be removed. We encourage all users to prepare their systems for this change.
The V4 REST API offers enhanced security and usability, including new and reorganized endpoints, as well as the removal of certain endpoints. For information on migrating from V3 to V4, please see the FME Flow REST API V4 documentation and click on the heading Migrating from REST API V4.
Full Guide: FME Flow Troubleshooting Guide
Are you encountering issues accessing or invoking the FME Flow (formerly FME Server) REST API? Please read below for some common troubleshooting tips, questions and resources.
In 2023, FME Server underwent a name change and is now known as FME Flow. Since this article discusses features present in previous versions of FME, it will refer to both names interchangeably, using the appropriate product name based on the year the feature was introduced. For more information on the rebranding, see our website.
Content Overview
- Initial Troubleshooting
- Common Issues
- Are you still experiencing issues?
- Have ideas on how to improve this?
Initial Troubleshooting
- Are you able to access the main http(s)://<hostname>:<port>/fmeserver page? If not, this may be a symptom of a larger issue.
- Log Files that may help identify errors include both FME Flow and Tomcat – these can be accessed via file system.
- <FMEFlowSystemShare>\resources\logs\core\current\fmeserver.log
- <FMEFlowSystemShare>\resources\logs\tomcat\catalina.log
- Can you try using a different web browser? You may also consider testing in a private window or emptying the cache or deleting cookies.
Are you seeing this error in the FME Flow UI? “There was a problem communicating with the REST API”
If so, view the developer tools to see if there are any errors. To do this, follow the steps below:
- Right-click and select Inspect
- In the side panel, go to the Network Tab
- Refresh the page
- See if there are any errors
If you do create a support case, please download the HAR file and attach it to the case.
Are you trying to access the FME Flow REST API in an HTTP call?
If so, try the following tips:
- What version of the REST API are you using? Try using the latest version.
- Are you receiving any response codes? You can cross-reference error codes with the REST API documentation.
- Are you using a valid token? Does it have the permissions for the component(s) you are accessing via REST? See Permissions by Task in Authorization in the FME Flow REST API | Token Management for the minimum permissions for each task. Avoid creating a token with all permissions.
Common Issues
“My FME Flow Token has changed or Expired”
Tokens can expire, which would cause REST API calls to fail. To learn how to manage tokens in FME Flow, see Token Management in FME Flow.
“I Receive a 401 or 403 Error from the REST API”
A 401 Unauthorized error means FME Flow did not recognize the token. The token is missing or invalid. For example, a made-up token returned the message “Failed to login,” and a request with no token returned “Unauthorized.” This is an authentication problem. For more about 401 errors, see 401 Unauthorized Error When Making FME Flow Request.
A 403 Forbidden error means FME Flow recognized the token, but the token does not have the permission for that action. This is an authorization problem. A 403 error can also mean the object does not exist. For example, training returned a 403 error on a download request because the repository is named Training. In a POST /jobs request, the same mistake returns a 404 error. The error message reads: Unauthorized request by user [username] due to lack of proper permissions or the object does not exist.
If you see a 403 error, check Permissions by Task in Authorization in the FME Flow REST API | Token Management for the minimum permissions for the task. For example, viewing a job result with GET /jobs/{id}/result needs Jobs > Manage, and Jobs > Access alone returns a 403 error. You can add a missing permission by clicking the token in Token Management, updating its permissions, and clicking Save. The change takes effect when you save. Do not create a token with All Permissions to fix a 403 error.
“REST API VX no longer works”
The FME Flow REST API has been released in multiple versions. Older versions of the REST API may already be deprecated (V1, V2). Review the FME Deprecations page for any announcements related to deprecations. As of FME 2025.1, the V3 REST API has entered deprecation. For information on migrating your workflows please see the V4 documentation at http://<yourFMEFlowHost>/fmeapiv4/docs/index.html
Are you still experiencing issues?
Please consider posting to the FME Community Q&A if you are still experiencing issues that are not addressed in this article. There are also different support channels available.
Have ideas on how to improve this?
You can add ideas or product suggestions to our Ideas Exchange.