The other day, I was trying to customize a list form using InfoPath, and I started receiving this error:
“InfoPath cannot connect to the server. The server may be offline, your computer might not be connected to the network, or InfoPath Forms Services 2010 might not be enabled on the server. To fix this problem, start by checking your network connection, and then trying again.”
Um… no, the server is up, I’m connected to the network, and InfoPath Forms Services is working just fine on every other site out there, thank you very much.
So… off to Google (or Bing) that error message, hoping for something fairly quick and simple. After a little digging, I came up with this blog post that pointed me down the right path:
To quote the meat of his post:
Since this was not an issue with other site collections we can narrow it down further that it is only with the InfoPath Site Features (IPFSSiteFeatures). This is a hidden feature in all site collections and can only be viewed through PowerShell. I found by simply disabling and re-enabling this feature fixed the problem.
Using PowerShell, you have to run the two commands:
PS C:\> Disable-SPFeature "IPFSSiteFeatures" -url "http://Server/Sites/SiteCollection"
PS C:\> Enable-SPFeature "IPFSSiteFeatures" -url "http://Server/Sites/SiteCollection"
Once I did that, everything went back to normal. I wish I knew a bit more behind the *why* of that happening, but I’m more into triage and keep moving… and this worked.
SharePoint Duffbert 
Wanted to mention another cause of the error presented in this post. In my case, our Sharepoint servers are hardened with Carbon Black, an IPS-like tool. It was prohibiting directory access and/or file saving during the publishing action.