Considerations
When using a File or URL published parameter configured with Path Selection > Single Path, you may see different behavior between FME Form and FME Flow. This can lead to unexpected translation failures, especially when working with file paths that contain spaces or when using transformers that expect a clean file path.
Why This Happens
This behavior is due to differences in how the parameter is handled across platforms:
In FME Form, the Single Path option restricts selection to a single file, and the file path is passed without quotation marks.
In FME Flow, the Single Path option may allow multiple file selections in some contexts (such as uploads). File paths containing spaces are automatically wrapped in double quotes. Even a single file path may be wrapped in quotes if spaces are present
These differences can cause issues for a few reasons. Some transformers do not handle quoted file paths correctly. For example, the FilenamePartExtractor transformer may fail to parse the path and connectors like FMEFlowResourceConnector (deprecated in FME 2025.0) or HTTP-based transformers (HTTPCaller or OpenAPICaller) may fail to read or write files when extra quotes are present
Behavior is inconsistent depending on whether the path contains spaces and whether the workspace is run in FME Form or FME Flow. As a result, workspaces that run successfully in FME Form may fail when published and run in FME Flow.
How to Resolve It
You can avoid this issue by adjusting how the parameter is defined:
Option 1: Change Path Selection Setting (Recommended)
In FME Form, update the published parameter by right-clicking on User Parameters in the Navigator pane and selecting Manage User Parameters. Select the File or URL parameter and scroll down to Items to Select. Change Path Selection to Existing Path
This ensures more consistent behavior across FME Form and FME Flow.
Option 2: Use a Text Parameter Instead
Another option is to replace the file or URL parameter with a text parameter. Users can manually provide the file path as a string. This avoids automatic quoting and gives you full control over the value passed into the workspace.
Additional Notes
This behavior is most noticeable when file paths contain spaces or when workspaces are run using uploaded resources in FME Flow. Some transformers (such as FeatureReader) may handle quoted paths correctly, but others will not, leading to inconsistent results.
Testing published parameters in both FME Form and FME Flow is recommended when working with file-based inputs.