CRM 2011/ 2013 OData Error: Expression of type 'System.Boolean' expected at position 0.

When you do OData Query, somehow you can receive this following error:

“Expression of type 'System.Boolean' expected at position 0.”

Resolution:

Check your ODataQuery

$select=tfp_Color,tfp_extrafreecopiesrateId,tfp_Mono&$filter=tfp_ProductCategoryId/Id (guid'" + productCategoryId + "')

don’t forget to add the operator

$select=tfp_Color,tfp_extrafreecopiesrateId,tfp_Mono&$filter=tfp_ProductCategoryId/Id eq (guid'" + productCategoryId + "')

Try to access using your browser:

Before:

After:

Hope it helps!