Release notes and improved error messages

re #18844

Framework/Kernel/src/ConfigService.cpp

@@ -1689,24 +1689,31 @@ bool ConfigServiceImpl::addDirectoryifExists(
 void ConfigServiceImpl::updateFacilities(const std::string &fName) {
   clearFacilities();
 
-  //search all of the instrument directories
+  // search all of the instrument directories
   std::vector<std::string> directoryNames = getInstrumentDirectories();
   std::string fileName = "";
   for (const auto &instrDir : directoryNames) {
     fileName = fName.empty() ? instrDir + "Facilities.xml" : fName;
 
-    Poco::File facilitiesFile(fileName); 
+    Poco::File facilitiesFile(fileName);
     // stop when you find the first one
     if (facilitiesFile.exists())
       break;
   }
-    
 
   // Set up the DOM parser and parse xml file
   Poco::XML::DOMParser pParser;
   Poco::AutoPtr<Poco::XML::Document> pDoc;
 
   try {
+    if (fileName.empty()) {
+      std::string directoryNamesList =
+          boost::algorithm::join(directoryNames, ", ");
+      throw std::runtime_error(
+          "Could not find a facilities info file! Searched for " +
+          directoryNamesList);
+    }
+
     try {
       pDoc = pParser.parse(fileName);
     } catch (...) {

docs/source/release/v3.9.0/framework.rst

@@ -5,6 +5,12 @@ Framework Changes
 .. contents:: Table of Contents
    :local:
 
+Facility Updates
+----------------
+
+- Mantid now supports automatic updates to the facilities.xml file in the same way that it does the instrument definitions.  This allows extensions and changes to the list of supported instruments without needing to install a new release of Mantid.
+  - This has been initially put into place to support a data file naming change for Vesuvio, but will help for future changes as well.
+
 Algorithms
 ----------