Before you can call OLE, you must set the current thread to single-threaded apartment (STA) mode, and make sure that your main function has STAThreadAttribute

Import and export function, when calling ShowDialog error, the workaround is as follows:

Entry point for the WinForm form:

        /// <summary>        /// The main entry point for the application.         /// </summary>         [STAThread]        privatestaticvoid  Main (string[] args)        {            application.enablevisualstyles ();            Application.setcompatibletextrenderingdefault (false);
　　　　　　  Application.Run (New LoginForm ());         }   

The error page program is as follows:

　　　 Public StringImportpath= ""; Global variable to display the import file path strength

        Private voidBtnimport_click (Objectsender, EventArgs e) {Thread Importthread=NewThread (NewThreadStart (Importdialog)); Importthread.setapartmentstate (ApartmentState.STA);            //Key Importthread.start (); Txtimportpath.text=Importpath; }         Public voidImportdialog () {OpenFileDialog Open=NewOpenFileDialog (); Open. Filter="Excel file |*.xls;*.xlsx"; if(Open. ShowDialog () = =DialogResult.OK) {Importpath=Open.                FileName;                Readexceltotable (Importpath);            Updatearea (); }        }

Before you can call OLE, you must set the current thread to single-threaded apartment (STA) mode, and make sure that your main function has STAThreadAttribute