diff --git a/src/main/java/io/cryostat/rules/Rules.java b/src/main/java/io/cryostat/rules/Rules.java
index 6acc0b9e6..d1df06e0f 100644
--- a/src/main/java/io/cryostat/rules/Rules.java
+++ b/src/main/java/io/cryostat/rules/Rules.java
@@ -39,6 +39,7 @@
 import org.jboss.resteasy.reactive.RestQuery;
 import org.jboss.resteasy.reactive.RestResponse;
 import org.jboss.resteasy.reactive.RestResponse.ResponseBuilder;
+import org.jboss.resteasy.reactive.server.ServerExceptionMapper;
 
 @Path("/api/v2/rules")
 public class Rules {
@@ -81,6 +82,14 @@ public RestResponse<V2Response> create(Rule rule) {
                 .build();
     }
 
+    @ServerExceptionMapper
+    public RestResponse<V2Response> mapException(RuleExistsException e) {
+        return ResponseBuilder.create(
+                        Response.Status.CONFLICT,
+                        V2Response.json(Response.Status.CONFLICT, e.getMessage()))
+                .build();
+    }
+
     @Transactional
     @PATCH
     @RolesAllowed("write")
@@ -147,7 +156,7 @@ public RestResponse<V2Response> delete(@RestPath String name, @RestQuery boolean
         return RestResponse.ok(V2Response.json(Response.Status.OK, null));
     }
 
-    static class RuleExistsException extends ClientErrorException {
+    public class RuleExistsException extends ClientErrorException {
         RuleExistsException(String ruleName) {
             super(
                     "Rule with name "