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Once in a while I get:
Unhandled Exception: System.InvalidCastException: QueryInterface for interface a.b.b failed.
at a.b.b.a(Int32& A_0)
at CoreLab.Common.DbMonitor.a(Object A_0, MonitorEventArgs A_1)
at CoreLab.Common.DbMonitor.a(DbMonitor A_0, MonitorTracePoint A_1, DbConnectionInternal A_2)
at CoreLab.Oracle.OracleMonitor.a(MonitorTracePoint A_0, OracleInternalConnection A_1)
at CoreLab.Oracle.OracleInternalConnection.a(Boolean A_0)
at CoreLab.Common.DbConnectionInternal.Dispose()
at CoreLab.Common.DbConnectionPoolGroup.c(Object A_0)
at CoreLab.Common.DbConnectionPool.RemoveObject(Object connection)
at CoreLab.Common.DbConnectionPoolGroup.a(DbConnectionPool A_0)
at CoreLab.Common.DbConnectionPoolGroup.b(Object A_0)
I am using version 3.0.0.0 with 8.1.7.4 server and an 8.1 client.

TIA
Frans

OraDirect .NET 3.0.0.0 has the problems with DbMonitor that we fixed in the last builds. Please try OraDirect .NET 3.01.5.

I updated to 3.1.5.0 and am still getting periodic errors:
An unhandled exception of type 'System.InvalidCastException' occurred in corelab.oracle.dll

Additional information: QueryInterface for interface a.b.b failed.

Apparently less debug info is being shown in the new version.

Here is the disassembly of CoreLab.Common.DbMonitor.a:
00000000 push ebp
00000001 mov ebp,esp
00000003 sub esp,28h
00000006 push edi
00000007 push esi
00000008 push ebx
00000009 xor eax,eax
0000000b mov dword ptr [ebp-0Ch],eax
0000000e mov esi,ecx
00000010 mov ebx,edx
00000012 mov edi,dword ptr [ebp+8]
00000015 cmp dword ptr [esi+18h],0
00000019 je 00000087
0000001b mov ecx,dword ptr [esi+18h]
0000001e lea edx,[ebp-0Ch]
00000021 mov eax,dword ptr [ecx]
00000023 mov eax,dword ptr [eax+0Ch]
00000026 mov eax,dword ptr [eax+0000026Ch]
0000002c call dword ptr [eax+8]
0000002f cmp dword ptr [ebp-0Ch],0
00000033 je 00000087
00000035 mov dword ptr [ebp-10h],esi
00000038 mov ecx,edi
0000003a cmp dword ptr [ecx],ecx
0000003c call dword ptr ds:[0D1B95D4h]
The problem ocurs at 0000002f.
I hope you can help.

TIA
Frans