This is a generic error message that QuickBooks provides and could indicate several different problems.
Exporting Invoices: An XML generation error is commonly caused by invoices with no line items or cost. To rectify this error, simply go to the invoices section of LMN Time and un-queue the invoices with a $0 total.
Exporting Estimates: An XML generation error can be caused by an invalid email address in LMN, extensive notes in work/ service area(s) or $0 value in work/ service area(s).
Invalid email address: Open CRM, select customer, contacts, ensure a valid email address is listed.
Extensive notes: Open Estimate, click work/ service area(s) and reduce or remove extensive notes.
$0 workarea/ service(s): Enter value or remove $0 work/service area(s).
An item in the estimate with a character such as ® or ™ (or something similar) in its name or description will also cause this error to occur. Special characters with similar appearances to regular characters have also been reported as causing this error. I.e : ’ vs ' The former is the incorrect character with the latter being correct.
Exporting Timesheets: An XML generation error can be a result of an emoji added to timesheet notes. To resolve, open timesheet and remove the emoji which will be in the first timesheet in the error log.