c# - System.Reflection.TargetInvocationException was unhandled in mscorlib.dll -

i'm trying read serial data dmm , think data gets corrupted sporadically. 95% of time can read data , display textbox fine once in while error:

system.reflection.targetinvocationexception unhandled in mscorlib.dll.

the innerexception is: message=input string not in correct format.

i'm new windows wpf , c# programming think means data received wasn't terminated properly.

here receive() code:

 private delegate void updateuitextdelegate(string text);     private void recieve(object sender, system.io.ports.serialdatareceivedeventargs e)     {         // collecting characters received our 'buffer' (string).         received_data = serial.readline();         dispatcher.invoke(dispatcherpriority.send, new updateuitextdelegate(writedata), received_data);                 } 

what's proper way handle corrupted data?

update: here's writedata():

 private void writedata(string text)     {         string mytextstripped;         string avgtext;         string textchar;         string currentfilteredtext;         double current;         double difference;         int range;         textbox2.text = mytext;                 // display raw string data         mytextstripped = text.substring(1, 7);  // remove chars after 7th char         mytextstrippedtextbox.text = mytextstripped;  // display trimmed string          if (mytextstripped[5] == '2')           // range 0 - 59.9 mv         {             range = 1;             mytextstripped = mytext.remove(4);  // keep first 4 chars             current = float.parse(mytextstripped);             current = current / 100;             mytextstrippedtextbox.background = brushes.yellow;         }         else if (mytextstripped[5] == '3')      // range 60mv - 600mv         {             range = 2;             mytextstripped = mytext.remove(4);  // keep first 4 chars             current = float.parse(mytextstripped);             current = current / 10;             mytextstrippedtextbox.background = brushes.yellowgreen;         }         else                                    // range 600mv+         {             range = 3;             mytextstripped = mytext.remove(4);  // keep first 4 chars             current = float.parse(mytextstripped);             mytextstrippedtextbox.background = brushes.palevioletred;         }         // filter results because readings jump visually determine value         difference = (current - currentfiltered);                   currentfiltered = currentfiltered + (filterfactor * difference);          avgtext = currentfiltered.tostring(".000");         avgtext = avgtext.trimstart('0');         currenttextbox.text = avgtext;     }