Mike Bashkatov said:

"4200", "14.0", "0.00", "0.00", "GST", "0", "1", "5.00", "0.00"
<salinvoice>

Try

</salinvoice>

and make sure there is an extra line feed after it.

You are the best ! Maybe I was trying for so long my eyes just refused to catch that error.

Also, maybe you can give me a hint where can I find detailed explanation about this line here: "Universal Construction", , , , , , , , , , , ,   meaning what goes to each of the empty spaces ?

The blanks are just the customer address fields.  If the customer already exists in the company file, the address is ignored.  If the customer does not exist, the address is used on import.

Most people post these questions in the Printing, Emailing and Importing forum or the Third-Party Development Partners forum.  You will find completed samples in one of those if you search SalInvoice or imp.

You can also find it in the SDK documentaiton and in the Knowledgebase.

I'm also trying to import sales invoices, but I'm struggling to find the correct way to import all the information, including jobsite, account number and salesperson. These 3 fields are part of sales invoices in Billing, but there is no mention of them in the SDK documentation for the SalInvoice .imp format, and they seem to be missing from the above as well. Is there no way to properly import invoices including all the info?

We can leave the salesperson and account as blank/default, but we do need to have the jobsite as part of the import, as it will change for each invoice.

Sorry, those fields are not part of the *.imp format and cannot be imported that way.

Projects (Jobsite) is available for import in the General Journal entries but that does not set up a receivable and it is rudimentary because it only allocates based on percentage.