最可能的原因是您的代码使用角色启动期间部署在同一台计算机上的外向COM服务器。稍后，您在该服务器中实例化一个对象，COM子系统为您提供代理对象。您的代码与COM服务器之间的通信是使用RPC完成的-RPC服务器是在外向COM服务器内部启动的。然后，COM服务器崩溃，您所拥有的只是一个现在不存在的COM服务器（和不存在的RPC服务器）的代理。当您在悬空代理上执行任何呼叫时，都会遇到此错误消息- RPC服务器不可用。

The most likely reason is that your code uses an out-proc COM server that you deploy on the same machine during role startup. Later you instantiate an object in that server and COM subsystem provides you with a proxy object. The communication between your code and the COM server is done using RPC - an RPC server is started inside the out-proc COM server. Then the COM server crashes and all you have is a proxy to a now non-existing COM server (and non-existing RPC server). When you perform any call on the dangling proxy you face this error message - RPC server is unavailable.

您必须查找导致COM服务器崩溃的原因以及为什么这样做并采取相应行动。

You have to find what COM server crashes and why it does so and act accordingly.