diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/api.yml b/spiffworkflow-backend/src/spiffworkflow_backend/api.yml
index ebf27ad82..b71bed93d 100755
--- a/spiffworkflow-backend/src/spiffworkflow_backend/api.yml
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/api.yml
@@ -1538,6 +1538,25 @@ paths:
                 items:
                   $ref: "#/components/schemas/User"
 
+  /users/exists/by-username:
+    post:
+      tags:
+        - Users
+      operationId: spiffworkflow_backend.routes.users_controller.user_exists_by_username
+      summary: Returns a true if user exists by username.
+      requestBody:
+        content:
+          application/json:
+            schema:
+              $ref: "#/components/schemas/User"
+      responses:
+        "200":
+          description: true if user exists
+          content:
+            application/json:
+              schema:
+                $ref: "#/components/schemas/OkTrue"
+
   /user-groups/for-current-user:
     get:
       tags:
diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/routes/users_controller.py b/spiffworkflow-backend/src/spiffworkflow_backend/routes/users_controller.py
index c2a832866..67a2a6e46 100644
--- a/spiffworkflow-backend/src/spiffworkflow_backend/routes/users_controller.py
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/routes/users_controller.py
@@ -1,13 +1,29 @@
 """Users_controller."""
+from typing import Any
+from typing import Dict
+
 import flask
 from flask import current_app
 from flask import g
 from flask import jsonify
 from flask import make_response
 
+from spiffworkflow_backend.exceptions.api_error import ApiError
 from spiffworkflow_backend.models.user import UserModel
 
 
+def user_exists_by_username(body: Dict[str, Any]) -> flask.wrappers.Response:
+    if "username" not in body:
+        raise ApiError(
+            error_code="username_not_given",
+            message="Username could not be found in post body.",
+            status_code=400,
+        )
+    username = body["username"]
+    found_user = UserModel.query.filter_by(username=username).first()
+    return make_response(jsonify({"user_found": found_user is not None}), 200)
+
+
 def user_search(username_prefix: str) -> flask.wrappers.Response:
     """User_search."""
     found_users = UserModel.query.filter(UserModel.username.like(f"{username_prefix}%")).all()  # type: ignore
diff --git a/spiffworkflow-backend/src/spiffworkflow_backend/services/authorization_service.py b/spiffworkflow-backend/src/spiffworkflow_backend/services/authorization_service.py
index f01a574f6..b608c4d9f 100644
--- a/spiffworkflow-backend/src/spiffworkflow_backend/services/authorization_service.py
+++ b/spiffworkflow-backend/src/spiffworkflow_backend/services/authorization_service.py
@@ -565,6 +565,7 @@ class AuthorizationService:
         permissions_to_assign.append(PermissionToAssign(permission="read", target_uri="/processes"))
         permissions_to_assign.append(PermissionToAssign(permission="read", target_uri="/service-tasks"))
         permissions_to_assign.append(PermissionToAssign(permission="read", target_uri="/user-groups/for-current-user"))
+        permissions_to_assign.append(PermissionToAssign(permission="create", target_uri="/users/exists/by-username"))
         permissions_to_assign.append(
             PermissionToAssign(permission="read", target_uri="/process-instances/find-by-id/*")
         )
diff --git a/spiffworkflow-frontend/src/components/ProcessInstanceListTable.tsx b/spiffworkflow-frontend/src/components/ProcessInstanceListTable.tsx
index 2681b6785..a13552f37 100644
--- a/spiffworkflow-frontend/src/components/ProcessInstanceListTable.tsx
+++ b/spiffworkflow-frontend/src/components/ProcessInstanceListTable.tsx
@@ -182,6 +182,10 @@ export default function ProcessInstanceListTable({
   const [processInitiatorText, setProcessInitiatorText] = useState<
     string | null
   >(null);
+  const [
+    processInitiatorNotFoundErrorText,
+    setProcessInitiatorNotFoundErrorText,
+  ] = useState<string>('');
 
   const lastRequestedInitatorSearchTerm = useRef<string>();
 
@@ -560,8 +564,17 @@ export default function ProcessInstanceListTable({
     return (reportMetadata as any).filter_by;
   };
 
+  const navigateToNewReport = (queryParamString: string) => {
+    removeError();
+    setProcessInstanceReportJustSaved(null);
+    setProcessInstanceFilters({});
+    navigate(`${processInstanceListPathPrefix}?${queryParamString}`);
+  };
+
   const applyFilter = (event: any) => {
     event.preventDefault();
+    setProcessInitiatorNotFoundErrorText('');
+
     const { page, perPage } = getPageInfoFromSearchParams(
       searchParams,
       undefined,
@@ -605,21 +618,33 @@ export default function ProcessInstanceListTable({
       queryParamString += `&report_id=${processInstanceReportSelection.id}`;
     }
 
-    if (processInitiatorSelection) {
-      queryParamString += `&process_initiator_username=${processInitiatorSelection.username}`;
-    } else if (processInitiatorText) {
-      queryParamString += `&process_initiator_username=${processInitiatorText}`;
-    }
-
     const reportColumnsBase64 = encodeBase64(JSON.stringify(reportColumns()));
     queryParamString += `&report_columns=${reportColumnsBase64}`;
     const reportFilterByBase64 = encodeBase64(JSON.stringify(reportFilterBy()));
     queryParamString += `&report_filter_by=${reportFilterByBase64}`;
 
-    removeError();
-    setProcessInstanceReportJustSaved(null);
-    setProcessInstanceFilters({});
-    navigate(`${processInstanceListPathPrefix}?${queryParamString}`);
+    if (processInitiatorSelection) {
+      queryParamString += `&process_initiator_username=${processInitiatorSelection.username}`;
+      navigateToNewReport(queryParamString);
+    } else if (processInitiatorText) {
+      HttpService.makeCallToBackend({
+        path: targetUris.userExists,
+        httpMethod: 'POST',
+        postBody: { username: processInitiatorText },
+        successCallback: (result: any) => {
+          if (result.user_found) {
+            queryParamString += `&process_initiator_username=${processInitiatorText}`;
+            navigateToNewReport(queryParamString);
+          } else {
+            setProcessInitiatorNotFoundErrorText(
+              `The provided username is invalid. Please type the exact username.`
+            );
+          }
+        },
+      });
+    } else {
+      navigateToNewReport(queryParamString);
+    }
   };
 
   const dateComponent = (
@@ -1143,6 +1168,8 @@ export default function ProcessInstanceListTable({
                     id="process-instance-initiator-search"
                     placeholder="Enter username"
                     labelText="Process Initiator"
+                    invalid={processInitiatorNotFoundErrorText !== ''}
+                    invalidText={processInitiatorNotFoundErrorText}
                     onChange={(event: any) => {
                       setProcessInitiatorText(event.target.value);
                       setRequiresRefilter(true);
diff --git a/spiffworkflow-frontend/src/hooks/UriListForPermissions.tsx b/spiffworkflow-frontend/src/hooks/UriListForPermissions.tsx
index d8c855340..c33946985 100644
--- a/spiffworkflow-frontend/src/hooks/UriListForPermissions.tsx
+++ b/spiffworkflow-frontend/src/hooks/UriListForPermissions.tsx
@@ -30,6 +30,7 @@ export const useUriListForPermissions = () => {
       processModelShowPath: `/v1.0/process-models/${params.process_model_id}`,
       secretListPath: `/v1.0/secrets`,
       userSearch: `/v1.0/users/search`,
+      userExists: `/v1.0/users/exists/by-username`,
     };
   }, [params]);