This error arose after upgrading to 8.5.
I have this code in a javascript:
'<a id="basketlink" href="Default.aspx?ID=<!--@Ecom:VariantCombination.Page.ID-->&' +
'ProductID=<!--@Ecom:VariantCombination.Product.ID-->&' +
'variantid=<!--@Ecom:VariantCombination.VariantID-->' +
'&cartcmd=add">' +
'Læg i kurven</a>';
This gets translated into: http://www.gottfred.dk/da-dk/shop/back-up-vikar-webshop/benklaeder.aspxProductID=PROD10905&variantid=VO33&cartcmd=add&EcomOrderLineFieldInput_tryk=undefined&quantity=1
Chaching the code into this, fixes the problem. But honestly, it shouldn't be that way.
'<a id="basketlink" href="Default.aspx?ID=<!--@Ecom:VariantCombination.Page.ID-->&' +
'?ProductID=<!--@Ecom:VariantCombination.Product.ID-->&' +
'variantid=<!--@Ecom:VariantCombination.VariantID-->' +
'&cartcmd=add">' +
'Læg i kurven</a>';