我会检查用户是否安装了代理软件，还检查了IE代理的设置。

还要检查用户是否具有正确的网关，以及用户是否可以访问您为VSTO扩展程序提供的网址的互联网连接。

如果是内部服务器，请确保将其排除在外代理。

Greets - Helmut

Hi,

We have a VSTO Outook add-in which we are deploying to users via clickonce. The installation is failing for one of our users with the following exception:

System.TimeoutException: The application could not be downloaded because a connection to the network could not be established. Ensure that you can connect to the network, and try again.

This seems to happen right at the end of the installation of the cusomization (i.e. when the progress bar is full). I read that this could be to do with MIME types in IIS, but the same installation works fine for most of my users, so this can't be the case. And, infact, this problem is solved by creating a brand new add-in, and not specifying and Installation Folder URL (just a Publishing Folder Location). So, I can work around this problem this way if necessary.

The main problem that I can't seem to resolve (which is again specific to this user's) computer, is that when an installation fails in this way, I don't seem to be able to fully remove the installation, and so when I try again to install the add-in, I get one of the following errors:

"Specified argument was out of the range of valid values. Parameter name: entryValue. "

OR

"Value does not fall within  the expected range".

Either way, I am no longer able to get any further than this subsequently, even after uninstalling. (When I've seen these problems on other users' computers, uninstalling and reinstalling the customization has worked fine).

These errors seem to be when vstoinstaller is updating the registry, but I have trawled through the registry to try and manually clean up but cannot find any trace of the assembly. How do I remove all traces of the partially installed addin? A record of the install attempt must be getting stored somewhere becuase, at the moment, I have to rebuild the add-in with a different assembly name, just to get as far as the "network connectivity" problem.

Also, any ideas on what could be causing the network connectivity issue? 

I've tried creating an "empty" outlook and Excel add-in and come up against the same issues in both on this user's computer. Interestingly deployment of a plain winforms app via clickonce worked fine.

Thanks in advance for your assistance. 

Hi,

I would check if the user has installed a proxy-software and also check the settings of IE for proxy.

Also check if the user has the correct gateway and that the internet-connection to the url you gave for the VSTO extension is accessible to the user.
If it's an internal server make sure it is excluded from proxy.

Greets - Helmut