System.DllNotFoundException: Unable to load DLL 'oci' when published to IIS

Question

I have a .net core application and I have to use System.Data.OracleClient.dll to connect with oracle db.

Everything works when I run this in VS2017 but when I publish and try to run the part that connects to the database I get an error:

System.DllNotFoundException: Unable to load DLL 'oci': The specified module could not be found. (Exception from HRESULT: 0x8007007E) at System.Data.OracleClient.Oci.OciCalls.OciNativeCalls.OCIEnvCreate(IntPtr& envhpp, OciEnvironmentMode mode, IntPtr ctxp, IntPtr malocfp, IntPtr ralocfp, IntPtr mfreep, Int32 xtramem_sz, IntPtr usrmempp)

Am I missing some kind of IIS module? I have x64 bit oracle in same PC.

Answer 1

可能是您缺少了OciCalls类调用的本机代码（可能是某些本机dll或类似的dll），或者找不到它在所查找的位置，无论如何，您都可以使用Assembly Binding Log Viewer对其进行调试以查看其位置探测以及缺少的东西。

Answer 2

For me finally helped following steps:

1. Got x86 Oracle Instant client from ( http://www.oracle.com/technetwork/database/features/instant-client/index-097480.html )
2. Added instant client folder to environment path to the first position so that it will precede all other oracle paths.
3. Restarted machine.