SenparcWeixinTenPayV3 TransactionsRequestData requestData = new_tenpayV3SettingTenPayV3_AppId _tenpayV3SettingTenPayV3_MchId body invoiceInvoiceIdToString new TenpayDateTimeD

The error message suggests that there is an issue with converting the value "3" to type 'System.String[]' at line 1, position 59 of the code snippet you provided.

To fix this issue, you need to ensure that the value being assigned to the 'detail.value' property is of type 'System.String[]'.

Please check the code surrounding this line and make sure that the value being assigned is a valid string array. If it is not, you may need to modify the code to provide a valid string array instead.