a "{op}" filter condition cannot be written ...

Warnings reference › source.odata.filter.refuse.*

Identifier

source.odata.filter.refuse.*

Raised by

The grid (core)

Since

1.74.0

What happened

filtersToOData used to fold a leaf it could not translate into the same empty string an empty group legitimately produces, then drop it from its parent and/or join - narrowing or widening the query past what the filter asked. It now throws instead. The ordinary pushdown path, whose splitFilters already keeps an unsupported operator out of what reaches this function via the adapter's declared capabilities.operators, is unaffected; this fires only when filtersToOData (or urlFor) is handed a tree containing an operator odataAdapter does not express directly.

The fix

Use only the operators odataAdapter declares (capabilities.operators), or fetch through a source that splits the filter into pushed and residual halves before calling filtersToOData.

Reference

Covered in full at the API reference.