ERR_INVALID_OPERATOR on Make.com: Invalid filter operator. Root cause: The filter or query expression uses a comparison operator that is not supported for the target field type. For example, using a 'contains' operator on a numeric field, or a 'greater than' operator on a multi-select field. Each field type has a restricted set of valid operators defined by the platform. Step 1: Identify the field type causing the error. In Make.com, open the failing scenario and find the filter or router condition that is erroring. Note the field name and check what data type it holds in the source module — is it text, number, date, boolean, or array? The error will occur when the operator does not match the field type. Step 2: Check Make.com's operator compatibility table. Make.com's filter operators are type-specific. Text fields support: equals, contains, starts with, ends with, matches pattern. Number fields support: equals, greater than, less than, between. Date fields support: is before, is after, is between. Boolean fields support: is true, is false. Arrays support: contains, does not contain. Step 3: Replace the invalid operator with a compatible one. In the filter condition, click the operator dropdown and select one that is valid for the field type. If you need to check whether a number field "contains" a value, use "equals" instead. If you need to check a text field for a numeric range, convert the field to a number type first using a Set Variable module. Step 4: Use a Set Variable module to cast the field type. If the field type is wrong (e.g. a number stored as text), add a Set Variable module before the filter. Use Make.com's parseNumber() or parseDate() functions to convert the value to the correct type, then filter on the converted variable. Step 5: Test the filter with sample data. After updating the operator, click "Run once" in Make.com with a real data bundle. Expand the filter module in the execution log to confirm it is evaluating correctly — green means the condition passed, red means it was filtered out. Test both a passing and a failing case.