Looping through keys in ASP.NET cache object

Don't use a foreach loop when removing items from any collection type- the foreach loop relies on using an enumerator which will NOT allow you to remove items from the collection (the enumerator will throw an exception if the collection it is iterating over has items added or removed from it).

Use a simple while to loop over the cache keys instead:

int i = 0;
while (i < Cache.Keys.Length){
   if (Cache.Keys(i).Contains(keyName){
      Cache.Remove(Cache.Keys(i))
   } 
   else{
      i ++;
   }
}