D365 X++ query to SQL Query

You're trying to compare or join a varchar (string) field with a bigint (numeric) field :

LEFT JOIN inventtransorigin io1 ON io1.inventtransid = inventtransorigin.recid

Here is the full query :

SELECT 
    inventtransorigin.itemid,
    inventtransorigin.referenceid,
    inventtransorigin.referencecategory,
    inventdim.inventbatchid,
    inventtrans.qty,
    inventtrans.unitid,
    inventtrans.costamountphysical,
    inventtrans.costamountposted
FROM inventtransorigin
JOIN inventtrans 
    ON inventtransorigin.recid = inventtrans.inventtransorigin
JOIN inventdim 
    ON inventtrans.inventdimid = inventdim.inventdimid
JOIN inventtablemodule 
    ON inventtrans.itemid = inventtablemodule.itemid 
    AND inventtablemodule.moduletype = 0
LEFT JOIN inventtransorigin io1 
    ON inventtrans.markingrefinventtransorigin = io1.recid
LEFT JOIN inventtransorigin io2 
    ON inventtrans.returninventtransorigin = io2.recid
LEFT JOIN inventtransorigin io3 
    ON inventtrans.inventtransorigin = io3.recid
WHERE 
    inventtransorigin.itemid = '100465' 
    AND inventdim.inventbatchid = 'hdh'