Active sales taxcode with percentage "" and type "" for date "" cannot be found.

There was no VAT percentage of x% (type x) in Yuki on (date).

You must ensure in Yuki that this missing VAT rate was created and was active on the specified date.

To do this, go to: Settings > Financial > VAT rates in Yuki and create the rate.
​PLEASE NOTE: the start date of the VAT rate must be on or before the invoice date of the invoice you are trying to book, otherwise it may VAT rate cannot be used in the booking.