Hi everyone,
After upgrading our FME Flow instance from 2025.2 to 2026.2, a workspace parameter with dynamic values stopped working in a Workspace App.
When opening the app, FME Flow shows the following error when testing the dynamic parameters:
Loading from Workspace
Kartenautomatisierungen/Kartenautomatisierung_ZUBA_PreScript_2.fmw
Error loading schema
Unable to generate dynamic parameters from source file.
Error was:
E:\appdata\fme\systemshare\resources\system\null\null\FeatureWriter\ZUBA.json
Please ensure the file exists and is readable.
A few observations:
- The same setup worked without issues in FME Flow 2025.2.
- The workspace itself executes successfully. It loads the JSON after the workspace is done.
- The error only occurs while loading the dynamic workspace parameter.
- The path contains
system\null\null\FeatureWriter\ZUBA.json, and the corresponding folders do not exist. - I never configured FME to write schema files to that location.
Has anyone seen a similar issue after upgrading to 2026.2? Is this a known problem with dynamic workspace parameters or FeatureWriter based schema generation?
There is a known issue (FMEFLOW-27717) regarding this, which should be resolved in 2026.2 but I still get this error.