Changed as suggested.

Emby.Server.Implementations/Plugins/PluginManager.cs

@@ -53,9 +53,7 @@ namespace Emby.Server.Implementations
             _logger = loggerfactory.CreateLogger<PluginManager>();
             _pluginsPath = pluginsPath;
             _appVersion = appVersion ?? throw new ArgumentNullException(nameof(appVersion));
-            _jsonOptions = JsonDefaults.GetOptions();
-            _jsonOptions.PropertyNameCaseInsensitive = true;
-            _jsonOptions.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
+            _jsonOptions = JsonDefaults.GetCamelCaseOptions();
             _config = config;
             _appHost = appHost;
             _imagesPath = imagesPath;
@@ -137,7 +135,8 @@ namespace Emby.Server.Implementations
                 var plugin = GetPluginByType(pluginServiceRegistrator.Assembly.GetType());
                 if (plugin == null)
                 {
-                    throw new NullReferenceException();
+                    _logger.LogError("Unable to find plugin in assembly {Assembly}", pluginServiceRegistrator.Assembly.FullName);
+                    continue;
                 }
 
                 CheckIfStillSuperceded(plugin);
@@ -440,6 +439,7 @@ namespace Emby.Server.Implementations
                     plugin.Instance = (IPlugin)instance;
                     var manifest = plugin.Manifest;
                     var pluginStr = plugin.Instance.Version.ToString();
+                    bool changed = false;
                     if (string.Equals(manifest.Version, pluginStr, StringComparison.Ordinal))
                     {
                         // If a plugin without a manifest failed to load due to an external issue (eg config),
@@ -447,11 +447,17 @@ namespace Emby.Server.Implementations
                         manifest.Version = pluginStr;
                         manifest.Name = plugin.Instance.Name;
                         manifest.Description = plugin.Instance.Description;
+                        changed = true;
                     }
 
+                    changed = changed || manifest.Status != PluginStatus.Active;
                     manifest.Status = PluginStatus.Active;
+
+                    if (changed)
+                    {
                         SaveManifest(manifest, plugin.Path);
                     }
+                }
 
                 _logger.LogInformation("Loaded plugin: {PluginName} {PluginVersion}", plugin.Name, plugin.Version);
 
@@ -577,8 +583,6 @@ namespace Emby.Server.Implementations
                 }
 
                 // Auto-create a plugin manifest, so we can disable it, if it fails to load.
-                // NOTE: This Plugin is marked as valid for two upgrades, at which point, it can be assumed the
-                // code base will have changed sufficiently to make it invalid.
                 manifest = new PluginManifest
                 {
                     Status = PluginStatus.RestartRequired,
@@ -586,7 +590,6 @@ namespace Emby.Server.Implementations
                     AutoUpdate = false,
                     Guid = metafile.GetMD5(),
                     TargetAbi = _appVersion.ToString(),
-                    MaxAbi = _nextVersion.ToString(),
                     Version = version.ToString()
                 };
 
@@ -678,11 +681,13 @@ namespace Emby.Server.Implementations
                         continue;
                     }
 
+                    if (manifest.Status != PluginStatus.DeleteOnStartup)
+                    {
                         manifest.Status = PluginStatus.DeleteOnStartup;
-
                         SaveManifest(manifest, entry.Path);
                     }
                 }
+            }
 
             // Only want plugin folders which have files.
             return versions.Where(p => p.DllFiles.Count != 0);

Emby.Server.Implementations/Updates/InstallationManager.cs

@@ -93,8 +93,7 @@ namespace Emby.Server.Implementations.Updates
             _httpClientFactory = httpClientFactory;
             _config = config;
             _zipClient = zipClient;
-            _jsonSerializerOptions = JsonDefaults.GetOptions();
-            _jsonSerializerOptions.PropertyNameCaseInsensitive = true;
+            _jsonSerializerOptions = JsonDefaults.GetCamelCaseOptions();
             _pluginManager = pluginManager;
         }
 

Jellyfin.Api/Controllers/PluginsController.cs

@@ -47,7 +47,7 @@ namespace Jellyfin.Api.Controllers
         {
             _installationManager = installationManager;
             _pluginManager = pluginManager;
-            _serializerOptions = JsonDefaults.GetOptions();
+            _serializerOptions = JsonDefaults.GetCamelCaseOptions();
             _config = config;
         }
 

MediaBrowser.Common/Json/JsonDefaults.cs

@@ -56,6 +56,7 @@ namespace MediaBrowser.Common.Json
         {
             var options = GetOptions();
             options.PropertyNamingPolicy = JsonNamingPolicy.CamelCase;
+            options.PropertyNameCaseInsensitive = true;
             return options;
         }
 

MediaBrowser.Model/Plugins/PluginStatus.cs

@@ -1,5 +1,3 @@
-#pragma warning disable CS1591 // Missing XML comment for publicly visible type or member
-#pragma warning disable SA1602 // Enumeration items should be documented
 namespace MediaBrowser.Model.Plugins
 {
     /// <summary>
@@ -7,12 +5,43 @@ namespace MediaBrowser.Model.Plugins
     /// </summary>
     public enum PluginStatus
     {
+        /// <summary>
+        /// This plugin requires a restart in order for it to load. This is a memory only status.
+        /// The actual status of the plugin after reload is present in the manifest.
+        /// eg. A disabled plugin will still be active until the next restart, and so will have a memory status of RestartRequired,
+        /// but a disk manifest status of Disabled.
+        /// </summary>
         RestartRequired = 1,
+
+        /// <summary>
+        /// This plugin is currently running.
+        /// </summary>
         Active = 0,
+
+        /// <summary>
+        /// This plugin has been marked as disabled.
+        /// </summary>
         Disabled = -1,
+
+        /// <summary>
+        /// This plugin does not meet the TargetAbi / MaxAbi requirements.
+        /// </summary>
         NotSupported = -2,
+
+        /// <summary>
+        /// This plugin caused an error when instantiated. (Either DI loop, or exception)
+        /// </summary>
         Malfunction = -3,
+
+        /// <summary>
+        /// This plugin has been superceded by another version.
+        /// </summary>
         Superceded = -4,
+
+        /// <summary>
+        /// An attempt to remove this plugin from disk will happen at every restart.
+        /// It will not be loaded, if unable to do so.
+        /// </summary>
         DeleteOnStartup = -5
     }
 }