diff --git a/code/services-core/control-service/src/main/java/nu/marginalia/control/ControlService.java b/code/services-core/control-service/src/main/java/nu/marginalia/control/ControlService.java
index c3a4e88f..e4b5d359 100644
--- a/code/services-core/control-service/src/main/java/nu/marginalia/control/ControlService.java
+++ b/code/services-core/control-service/src/main/java/nu/marginalia/control/ControlService.java
@@ -54,7 +54,8 @@ public class ControlService extends Service {
                           DataSetsService dataSetsService,
                           ControlNodeService controlNodeService,
                           ControlDomainRankingSetsService controlDomainRankingSetsService,
-                          ControlActorService controlActorService
+                          ControlActorService controlActorService,
+                          ControlErrorHandler errorHandler
                       ) throws IOException {
 
         super(params);
@@ -81,6 +82,8 @@ public class ControlService extends Service {
         domainComplaintService.register();
         randomExplorationService.register();
 
+        errorHandler.register();
+
         var indexRenderer = rendererFactory.renderer("control/index");
         var eventsRenderer = rendererFactory.renderer("control/sys/events");
         var serviceByIdRenderer = rendererFactory.renderer("control/sys/service-by-id");
@@ -106,6 +109,7 @@ public class ControlService extends Service {
 
         Spark.get("/public/:resource", this::serveStatic);
 
+
         monitors.subscribe(this::logMonitorStateChange);
 
         controlActorService.startDefaultActors();
diff --git a/code/services-core/control-service/src/main/java/nu/marginalia/control/ControlValidationError.java b/code/services-core/control-service/src/main/java/nu/marginalia/control/ControlValidationError.java
new file mode 100644
index 00000000..29ff7317
--- /dev/null
+++ b/code/services-core/control-service/src/main/java/nu/marginalia/control/ControlValidationError.java
@@ -0,0 +1,15 @@
+package nu.marginalia.control;
+
+public class ControlValidationError extends RuntimeException {
+    public final String title;
+    public final String messageLong;
+    public final String redirect;
+
+    public ControlValidationError(String title, String messageLong, String redirect) {
+        super(title);
+
+        this.title = title;
+        this.messageLong = messageLong;
+        this.redirect = redirect;
+    }
+}
diff --git a/code/services-core/control-service/src/main/java/nu/marginalia/control/sys/svc/ControlDomainRankingSetsService.java b/code/services-core/control-service/src/main/java/nu/marginalia/control/sys/svc/ControlDomainRankingSetsService.java
index 362ef0f8..73f19611 100644
--- a/code/services-core/control-service/src/main/java/nu/marginalia/control/sys/svc/ControlDomainRankingSetsService.java
+++ b/code/services-core/control-service/src/main/java/nu/marginalia/control/sys/svc/ControlDomainRankingSetsService.java
@@ -3,6 +3,7 @@ package nu.marginalia.control.sys.svc;
 import com.google.inject.Inject;
 import com.zaxxer.hikari.HikariDataSource;
 import nu.marginalia.control.ControlRendererFactory;
+import nu.marginalia.control.ControlValidationError;
 import nu.marginalia.control.Redirects;
 import nu.marginalia.db.DomainRankingSetsService;
 import spark.Request;
@@ -41,6 +42,7 @@ public class ControlDomainRankingSetsService {
     private Object alterSetModel(Request request, Response response) throws SQLException {
         final String act = request.queryParams("act");
         final String id = request.params("id");
+
         if ("update".equals(act)) {
             domainRankingSetsService.upsert(new DomainRankingSetsService.DomainRankingSet(
                     id,
@@ -54,18 +56,26 @@ public class ControlDomainRankingSetsService {
         else if ("delete".equals(act)) {
             var model = domainRankingSetsService.get(id).orElseThrow();
             if (model.isSpecial()) {
-                throw new IllegalArgumentException("Cannot delete special ranking set");
+                throw new ControlValidationError("Cannot delete special ranking set",
+                        """
+                                SPECIAL data sets are reserved by the system and can not be deleted.
+                                """,
+                        "/domain-ranking-sets");
             }
             domainRankingSetsService.delete(model);
             return "";
         }
         else if ("create".equals(act)) {
             if (domainRankingSetsService.get(request.queryParams("name")).isPresent()) {
-                throw new IllegalArgumentException("Ranking set with that name already exists");
+                throw new ControlValidationError("Ranking set with that name already exists",
+                        """
+                                Ensure the new data set has a unique name and try again.
+                                """,
+                        "/domain-ranking-sets");
             }
 
             domainRankingSetsService.upsert(new DomainRankingSetsService.DomainRankingSet(
-                    request.queryParams("name"),
+                    request.queryParams("name").toUpperCase(),
                     request.queryParams("description"),
                     DomainRankingSetsService.DomainSetAlgorithm.valueOf(request.queryParams("algorithm")),
                     Integer.parseInt(request.queryParams("depth")),
@@ -74,7 +84,10 @@ public class ControlDomainRankingSetsService {
             return "";
         }
 
-        throw new UnsupportedOperationException();
+        throw new ControlValidationError("Unknown action", """
+                An unknown action was requested and the system does not understand how to act on it.
+                """,
+            "/domain-ranking-sets");
     }
 
     private Object rankingSetsModel(Request request, Response response) {
diff --git a/code/services-core/control-service/src/main/java/nu/marginalia/control/sys/svc/ControlErrorHandler.java b/code/services-core/control-service/src/main/java/nu/marginalia/control/sys/svc/ControlErrorHandler.java
new file mode 100644
index 00000000..277d84fc
--- /dev/null
+++ b/code/services-core/control-service/src/main/java/nu/marginalia/control/sys/svc/ControlErrorHandler.java
@@ -0,0 +1,35 @@
+package nu.marginalia.control.sys.svc;
+
+import com.google.inject.Inject;
+import nu.marginalia.control.ControlRendererFactory;
+import nu.marginalia.control.ControlValidationError;
+import spark.Request;
+import spark.Response;
+import spark.Spark;
+
+import java.util.Map;
+
+public class ControlErrorHandler {
+    private final ControlRendererFactory.Renderer renderer;
+
+    @Inject
+    public ControlErrorHandler(ControlRendererFactory rendererFactory) {
+        this.renderer = rendererFactory.renderer("control/error");
+    }
+
+    public void render(ControlValidationError error, Request request, Response response) {
+        String text = renderer.render(
+                Map.of(
+                "title", error.title,
+                "messageLong", error.messageLong,
+                "redirect", error.redirect
+                )
+        );
+
+        response.body(text);
+    }
+
+    public void register() {
+        Spark.exception(ControlValidationError.class, this::render);
+    }
+}
diff --git a/code/services-core/control-service/src/main/resources/templates/control/error.hdb b/code/services-core/control-service/src/main/resources/templates/control/error.hdb
new file mode 100644
index 00000000..d973163d
--- /dev/null
+++ b/code/services-core/control-service/src/main/resources/templates/control/error.hdb
@@ -0,0 +1,25 @@
+<!DOCTYPE html>
+<html>
+<head>
+    <title>Control Service: Error</title>
+    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
+    <link rel="stylesheet" href="/style.css" />
+    {{> control/partials/head-includes }}
+</head>
+<body>
+{{> control/partials/nav}}
+<div class="container">
+    <h1 class="my-3">Error: {{title}}</h1>
+    <div class="my-3 p-3 border bg-light">
+        <p>{{messageLong}}</p>
+        <a href="{{redirect}}">Go back</a>
+    </div>
+</div>
+</body>
+{{> control/partials/foot-includes }}
+<script>
+    window.setInterval(() => {
+        refresh(["processes", "services", "jobs", "events"]);
+    }, 2000);
+</script>
+</html>
diff --git a/code/services-core/control-service/src/main/resources/templates/control/sys/domain-ranking-sets.hdb b/code/services-core/control-service/src/main/resources/templates/control/sys/domain-ranking-sets.hdb
index 79fcfb32..ba395319 100644
--- a/code/services-core/control-service/src/main/resources/templates/control/sys/domain-ranking-sets.hdb
+++ b/code/services-core/control-service/src/main/resources/templates/control/sys/domain-ranking-sets.hdb
@@ -32,6 +32,21 @@
     <div class="my-3">
         <a href="/domain-ranking-sets/new" class="btn btn-primary">New Domain Ranking Set</a>
     </div>
+
+
+    <div class="border my-3 p-3 bg-light">
+        <p>Several reserved ranking sets are available for use in the query parameters.</p>
+        <dl>
+            <dt>NONE</dt><dd>Placeholder for no restriction on the domains returned.
+                             Does nothing, and exists only to prevent a new ranking
+                             set from being created with this name.</dd>
+            <dt>RANK</dt><dd>Used to calculate the domain ranking for a given domain.
+                This affects the order they are stored in the index, and increases the odds they'll
+                even be considered within the time restrictions of the query.</dd>
+            <dt>BLOGS</dt><dd>Returns a fixed list of domains, configurable in <a href="/datasets">Datasets</a>.
+                Changes to this list will not be reflected in the index until the next time the index is rebuilt.</dd>
+        </dl>
+    </div>
 </div>
 </body>
 {{> control/partials/foot-includes }}
diff --git a/code/services-core/control-service/src/main/resources/templates/control/sys/new-domain-ranking-set.hdb b/code/services-core/control-service/src/main/resources/templates/control/sys/new-domain-ranking-set.hdb
index 7c086276..bd68e0c4 100644
--- a/code/services-core/control-service/src/main/resources/templates/control/sys/new-domain-ranking-set.hdb
+++ b/code/services-core/control-service/src/main/resources/templates/control/sys/new-domain-ranking-set.hdb
@@ -11,17 +11,18 @@
     <form method="post" action="?act=create">
     <table class="table">
         <tr>
-            <th>Name</th>
+            <th><label for="name">Name</label></th>
             <td>
-                <input pattern="\w+" type="text" value="{{name}}" id="name" name="name" />
+                <input pattern="\w+" type="text" value="{{name}}" id="name" name="name" style="text-transform: uppercase" />
                 <div>
-                    <small class="text-muted">The name is how the ranking set is identified in the query parameters,
+                    <small class="text-muted">Must be all letters.
+                        The name is how the ranking set is identified in the query parameters,
                         and also decides the file name of the persisted ranking set definition. Keep it simple.</small>
                 </div>
             </td>
         </tr>
         <tr>
-            <th>Algorithm</th>
+            <th><label for="algorithm">Algorithm</label></th>
             <td>
                 <select id="algorithm" name="algorithm">
                     <option value="LINKS_PAGERANK">LINKS_PAGERANK</option>
@@ -38,7 +39,7 @@
             </td>
         </tr>
         <tr>
-            <th>Description</th>
+            <th><label for="description">Description</label></th>
             <td>
                 <input type="text" value="{{description}}" id="description" name="description" {{#if special}}disabled{{/if}} />
                 <div>
@@ -47,15 +48,15 @@
             </td>
         </tr>
         <tr>
-            <th>Depth</th>
+            <th><label for="depth">Depth</label></th>
             <td>
                 <input pattern="\d+" type="text" value="{{depth}}" id="depth" name="depth" />
                 <div>
-                    <small class="text-muted">Up to this number of domains are ranked, the rest are excluded.</small>
+                    <small class="text-muted">Number. Up to this number of domains are ranked, the rest are excluded.</small>
                 </div>
             </td>
         </tr>
-        <tr><th colspan="2">Definition</th></tr>
+        <tr><th colspan="2"><label for="definition">Definition</label></th></tr>
         <tr><td colspan="2">
             <textarea name="definition" id="definition" rows="10" style="width: 100%">{{definition}}</textarea>
             <div>
diff --git a/code/services-core/control-service/src/main/resources/templates/control/sys/update-domain-ranking-set.hdb b/code/services-core/control-service/src/main/resources/templates/control/sys/update-domain-ranking-set.hdb
index 3e228c67..c36b9a5f 100644
--- a/code/services-core/control-service/src/main/resources/templates/control/sys/update-domain-ranking-set.hdb
+++ b/code/services-core/control-service/src/main/resources/templates/control/sys/update-domain-ranking-set.hdb
@@ -12,7 +12,7 @@
     <form method="post" action="?act=update">
     <table class="table" id="update-form">
         <tr>
-            <th>Name</th>
+            <th><label for="name">Name</label></th>
             <td>
                 {{#if special}}<input type="hidden" name="name" value="{{name}}" />{{/if}}
                 <input type="text" value="{{name}}" id="name" name="name" {{#if special}}disabled{{/if}} />
@@ -23,7 +23,7 @@
             </td>
         </tr>
         <tr>
-            <th>Algorithm</th>
+            <th><label for="algorithm">Algorithm</label></th>
             <td>
                 {{#if special}}<input type="hidden" name="algorithm" value="{{algorithm}}" />{{/if}}
                 <select id="algorithm" name="algorithm" {{#if special}}disabled{{/if}}>
@@ -44,7 +44,7 @@
             </td>
         </tr>
         <tr>
-            <th>Description</th>
+            <th><label for="description">Description</label></th>
             <td>
                 {{#if special}}<input type="hidden" name="description" value="{{description}}" />{{/if}}
                 <input type="text" value="{{description}}" id="description" name="description" {{#if special}}disabled{{/if}} />
@@ -54,15 +54,15 @@
             </td>
         </tr>
         <tr>
-            <th>Depth</th>
+            <th><label for="depth">Depth</label></th>
             <td>
                 <input type="text" value="{{depth}}" id="depth" name="depth" />
                 <div>
-                    <small class="text-muted">Up to this number of domains are ranked, the rest are excluded.</small>
+                    <small class="text-muted">Number.  Up to this number of domains are ranked, the rest are excluded.</small>
                 </div>
             </td>
         </tr>
-        <tr><th colspan="2">Definition</th></tr>
+        <tr><th colspan="2"><label for="definition">Definition</label></th></tr>
         <tr><td colspan="2">
             <textarea name="definition" id="definition" rows="10" style="width: 100%">{{definition}}</textarea>
             <div>