I have Excel 2013. I am importing a text file into PowerPivot and using Pivot Tables and slicers to sort and analyze the data. I can reimport the file into PowerPivot just fine, but when I try to refresh the data, I get the error: "Failed to connect to the server. Reason: Unspecified error." This is very frustrating because I have to rebuild my pivot tables every time I close and reopen this file. I have tried to import the data as a csv file and excel file rather than a txt file, but the same error occurs. Windows is up to date on my computer. Has anyone run into this problem before?