# graphql-kotlin


01/06/2022, 11:41 AM
Hi everyone, I'm trying to upgrade from kotlin 1.4 to 1.5 in the project with expedia v3.6.1 and get the following error:
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Caused by: com.expediagroup.graphql.exceptions.InvalidInputFieldTypeException: Argument cannot be an interface or a union, parameter #2 output of fun aaa.FuzzyDate.`write$Self`(aaa.FuzzyDate, kotlinx.serialization.encoding.CompositeEncoder, kotlinx.serialization.descriptors.SerialDescriptor): kotlin.Unit
It sounds like red herring to me but maybe there is something I can fix? Or is it incompatibility between expedia 3 and kotlin 1.5? The class that is failing looks like this
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data class FuzzyDate(val year: Int? = null, val month: Int? = null, val day: Int? = null, val current: Boolean? = false)
I'm actually planning to upgrade expedia to v5 as well but would like to do it step by step if possible