I'm using the umod.rust 3.0 source: https://github.com/theumod/uMod.Rust and once compiled and put into the `C:\rustserver\RustDedicated_Data\Managed` server directory on my local instance of the server I get this error:

Using Universal provider for game 'Rust'
Couldn't check for update to Compiler.exe
System.Net.WebException: Error: TrustFailure (The authentication or decryption has failed.) ---> System.IO.IOException: The authentication or decryption has failed. ---> System.IO.IOException: The authentication or decryption has failed. ---> Mono.Security.Protocol.Tls.TlsException: Invalid certificate received from server. Error code: 0xffffffff800b010a
at Mono.Security.Protocol.Tls.RecordProtocol.EndReceiveRecord (System.IAsyncResult asyncResult) [0x00037] in <59f5789d548a4d9d86fbc012db4951c0>:0
at Mono.Security.Protocol.Tls.SslClientStream.SafeEndReceiveRecord (System.IAsyncResult ar, System.Boolean ignoreEmpty) [0x00000] in <59f5789d548a4d9d86fbc012db4951c0>:0
at Mono.Security.Protocol.Tls.SslClientStream.NegotiateAsyncWorker (System.IAsyncResult result) [0x00071] in <59f5789d548a4d9d86fbc012db4951c0>:0
--- End of inner exception stack trace ---
at Mono.Security.Protocol.Tls.SslClientStream.EndNegotiateHandshake (System.IAsyncResult result) [0x00032] in <59f5789d548a4d9d86fbc012db4951c0>:0
at Mono.Security.Protocol.Tls.SslStreamBase.AsyncHandshakeCallback (System.IAsyncResult asyncResult) [0x0000c] in <59f5789d548a4d9d86fbc012db4951c0>:0
--- End of inner exception stack trace ---
at Mono.Security.Protocol.Tls.SslStreamBase.EndRead (System.IAsyncResult asyncResult) [0x0004b] in <59f5789d548a4d9d86fbc012db4951c0>:0
at Mono.Net.Security.Private.LegacySslStream.EndAuthenticateAsClient (System.IAsyncResult asyncResult) [0x0000e] in <4b9f316768174388be8ae5baf2e6cc02>:0
at Mono.Net.Security.Private.LegacySslStream.AuthenticateAsClient (System.String targetHost, System.Security.Cryptography.X509Certificates.X509CertificateCollection clientCertificates, System.Security.Authentication.SslProtocols enabledSslProtocols, System.Boolean checkCertificateRevocation) [0x0000e] in <4b9f316768174388be8ae5baf2e6cc02>:0
at Mono.Net.Security.MonoTlsStream.CreateStream (System.Byte[] buffer) [0x0007b] in <4b9f316768174388be8ae5baf2e6cc02>:0
at System.Net.WebConnection.CreateStream (System.Net.HttpWebRequest request) [0x00073] in <4b9f316768174388be8ae5baf2e6cc02>:0
--- End of inner exception stack trace ---
at System.Net.HttpWebRequest.EndGetResponse (System.IAsyncResult asyncResult) [0x00058] in <4b9f316768174388be8ae5baf2e6cc02>:0
at System.Net.HttpWebRequest.GetResponse () [0x0000e] in <4b9f316768174388be8ae5baf2e6cc02>:0
at uMod.Plugins.PluginCompiler.UpdateCheck () [0x00028] in <220113c17e27494c837cb8b833b3e602>:0
Loading plugins...


Anyone know why I would be getting this?

uMod builds are in development still and not supported at this time. Please use the Oxide builds as mentioned in your other thread.