Currently, the ArcGIS Enterprise update tool that is used to find and install Esri patches does not include the web adaptor. Considering the web adaptor is a component of ArcGIS Enterprise, and the tool is called "Check for ArcGIS Enterprise Updates", web adaptor updates should be included. It is misleading (and also an inconvenience) for web adaptor updates to not be included in that tool.
Currently, the 11.1 web adaptor is loaded with bugs that Esri has already released one patch for, with more coming in the next month or so. I would not have known there was an update to it if it wasn't for finding it in a geonet post. Since web adaptor updates aren't really published anywhere, other people could potentially be experiencing this problem that the update fixes. But, they won't know about it unless they reach out to Esri support, search geonet, etc.
