Excel export failing in v3.8

We recently upgraded to 3.8 and having issues with product export. I understand that the whole functionality has been changed.

When trying to Export to Excel Selected files, we see an internal server error.

When trying to Export to Excel All found, we get the following message "The total length of a DataValidation list cannot exceed 255 characters". Full details below:

System.InvalidOperationException: The total length of a DataValidation list cannot exceed 255 characters at OfficeOpenXml.DataValidation.Formulas.ExcelDataValidationFormulaList.values_ListChanged(Object sender, EventArgs e) at OfficeOpenXml.DataValidation.Formulas.ExcelDataValidationFormulaList.DataValidationList.OnListChanged() at Nop.Services.ExportImport.Help.PropertyManager`1.WriteToXlsx(ExcelWorksheet worksheet, Int32 row, Int32 cellOffset) at Nop.Services.ExportImport.ExportManager.ExportProductsToXlsxWithAttributes(PropertyByName`1[] properties, IEnumerable`1 itemsToExport) at Nop.Admin.Controllers.ProductController.ExportExcelAll(ProductListModel model)


Between this and the registration process being broken, our business is at a standstill.

I am getting the same issue, did you ever figure this out? I haven't applied the performance fix I was emailed about   for 3.8 I am wondering if that is the issue.

Do you have Vendors?  How many?

I suspect this might be the cause of the problem

                new PropertyByName<Product>("Vendor", p => p.VendorId, IgnoreExportPoductProperty(p => p.Vendor))
                {
                    DropDownElements = _vendorService.GetAllVendors(showHidden:true).Select(v => v as BaseEntity).ToSelectList(p => (p as Vendor).Return(v => v.Name, String.Empty)),
                    AllowBlank = true
                },

That was the problem. It was a bug in how the validators were being created and we have a lot of vendors so it reached the 255 character max of the formula.

There was a changeset that fixed this that they posted on another thread.  I downloaded the changeset and integrated it in my local code base and it fixed the issue.

This problem has been solved already, you can see the implementation details  in this ticket.