Rob Schripsema Rob Schripsema - 1 month ago 17
C# Question

Could not establish trust relationship for SSL/TLS secure channel -- SOAP

I have a simple web service call, generated by a .NET (C#) 2.0 windows app, via the web service proxy generated by Visual Studio, for a web service also written in C# (2.0). This has worked for several years, and continues to do so at the dozen or so places where it is running.

A new installation at a new site is running into a problem. When attempting to invoke the web service, it fails with the message saying:


Could not establish a trust relationship for the SSL/TLS secure
channel


The URL of the web service uses SSL (https://) -- but this has been working for a long time (and continues to do so) from many other locations.

Where do I look? Could this be a security issue between Windows and .NET that is unique to this install? If so, where do I set up trust relationships? I'm lost!

Answer

Thoughts (based on pain in the past):

  • do you have DNS and line-of-sight to the server?
  • are you using the correct name from the certificate?
  • is the certificate still valid?
  • is a badly configured load balancer messing things up?
  • does the new server machine have the clock set correctly (i.e. so that the UTC time is correct [ignore local time, it is largely irrelevent]) - this certainly matters for WCF, so may impact regular SOAP?
  • is there a certificate trust chain issue? if you browse from the server to the soap service, can you get SSL?
  • is the server's machine-level proxy set correctly? (which different to the user's proxy); see proxycfg for XP / 2003 (not sure about Vista etc)