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Why can't catch an internal exception?

I am trying to catch a database exception when the database server is down. We use Sybase IAnywhere.

I use regular C # try catch to get the database exception name.

try
{
//code here
}
catch (Exception ex)
{
Logging.Log.logItem(LogType.Exception, "Exception in isDBRunning", "App_Startup::isDBRunning() ", "GetBaseException=" + ex.GetBaseException().ToString() + "\nMessage=" + ex.Message + "\nStackTrace: " + ex.StackTrace + "\nInnerException: " + ex.InnerException);
}

An exception is the following:

GetBaseException=iAnywhere.Data.SQLAnywhere.SAException: Database server not found
   at iAnywhere.Data.SQLAnywhere.SAConnection.Open()
   at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure)
Message=The underlying provider failed on Open.
StackTrace:    at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure)
   at System.Data.EntityClient.EntityConnection.Open()
   at System.Data.Objects.ObjectContext.EnsureConnection()
   at System.Data.Objects.ObjectQuery`1.GetResults(Nullable`1 forMergeOption)
   at System.Data.Objects.ObjectQuery`1.System.Collections.Generic.IEnumerable<T>.GetEnumerator()
   at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source)
   at System.Data.Objects.ELinq.ObjectQueryProvider.<GetElementFunction>b__2[TResult](IEnumerable`1 sequence)
   at System.Data.Objects.ELinq.ObjectQueryProvider.ExecuteSingle[TResult](IEnumerable`1 query, Expression queryRoot)
   at System.Data.Objects.ELinq.ObjectQueryProvider.System.Linq.IQueryProvider.Execute[S](Expression expression)
   at System.Linq.Queryable.Count[TSource](IQueryable`1 source)
   at Analogic.SystemSoftware.App.isDBRunning() in C:\workspace\SystemSoftware\SystemSoftware\src\startup\App.xaml.cs:line 158
InnerException: iAnywhere.Data.SQLAnywhere.SAException: Database server not found
   at iAnywhere.Data.SQLAnywhere.SAConnection.Open()
   at System.Data.EntityClient.EntityConnection.OpenStoreConnectionIf(Boolean openCondition, DbConnection storeConnectionToOpen, DbConnection originalConnection, String exceptionCode, String attemptedOperation, Boolean& closeStoreConnectionOnFailure)

So, I think that iAnywhere.Data.SQLAnywhere.SAExceptionis the real exception that I have to handle. Then I added a catch for him:

try
{
 //code here
}
catch (iAnywhere.Data.SQLAnywhere.SAException ex)
{
Logging.Log.logItem(LogType.Exception, "Exception in isDBRunning 1", "App_Startup::isDBRunning() ", "GetBaseException=" + ex.GetBaseException().ToString() + "\nMessage=" + ex.Message + "\nStackTrace: " + ex.StackTrace + "\nInnerException: " + ex.InnerException);
}

catch (Exception ex)
{
 Logging.Log.logItem(LogType.Exception, "Exception in isDBRunning", "App_Startup::isDBRunning() ", "GetBaseException=" + ex.GetBaseException().ToString() + "\nMessage=" + ex.Message + "\nStackTrace: " + ex.StackTrace + "\nInnerException: " + ex.InnerException);
}

But iAnywhere.Data.SQLAnywhere.SAExceptionNOT caught. I will catch anyway Exception. why?

+5
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5 answers

Because what is selected is not a SAException. Try printing the exception directly instead of calling GetBaseException ().

+4

Catch , , GetBaseException () InnerException, .

, ( - ), .

+6

SAException, . , . :

catch (Exception ex) {
    Console.WriteLine(ex.GetType().FullName;
    //...
}
+3

, , . GetBaseException() , .

+1

- :

try
{
    //code here
}
catch (Exception ex)
{
    if (ex.GetBaseException() is iAnywhere.Data.SQLAnywhere.SAException)
    {
        // log or handle known exception
    }
    else
    {
        // log unexpected exception
    } 
}

, , , Exception .

+1

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