diff --git a/atst/routes/errors.py b/atst/routes/errors.py
index b539ce2a..40a00c26 100644
--- a/atst/routes/errors.py
+++ b/atst/routes/errors.py
@@ -9,12 +9,12 @@ def make_error_pages(app):
     # pylint: disable=unused-variable
     def not_found(e):
         app.logger.error(e.message)
-        return render_template("not_found.html"), 404
+        return render_template("error.html", message="Not Found"), 404
 
     @app.errorhandler(exceptions.UnauthenticatedError)
     # pylint: disable=unused-variable
     def unauthorized(e):
         app.logger.error(e.message)
-        return render_template("unauthenticated.html"), 401
+        return render_template("error.html", message="Log in Failed"), 401
 
     return app
diff --git a/atst/routes/workspaces.py b/atst/routes/workspaces.py
index 31f35f38..583d4b65 100644
--- a/atst/routes/workspaces.py
+++ b/atst/routes/workspaces.py
@@ -10,7 +10,7 @@ from flask import (
     url_for,
 )
 
-from atst.domain.exceptions import UnauthorizedError
+from atst.domain.exceptions import UnauthorizedError, AlreadyExistsError
 from atst.domain.projects import Projects
 from atst.domain.reports import Reports
 from atst.domain.workspaces import Workspaces
@@ -200,14 +200,19 @@ def create_member(workspace_id):
     form = NewMemberForm(http_request.form)
 
     if form.validate():
-        new_member = Workspaces.create_member(g.current_user, workspace, form.data)
-        return redirect(
-            url_for(
-                "workspaces.workspace_members",
-                workspace_id=workspace.id,
-                newMemberName=new_member.user_name,
+        try:
+            new_member = Workspaces.create_member(g.current_user, workspace, form.data)
+            return redirect(
+                url_for(
+                    "workspaces.workspace_members",
+                    workspace_id=workspace.id,
+                    newMemberName=new_member.user_name,
+                )
+            )
+        except AlreadyExistsError:
+            return render_template(
+                "error.html", message="There was an error processing your request."
             )
-        )
     else:
         return render_template(
             "workspaces/members/new.html", workspace=workspace, form=form
diff --git a/templates/not_found.html b/templates/error.html
similarity index 54%
rename from templates/not_found.html
rename to templates/error.html
index 59cc223f..c8714c01 100644
--- a/templates/not_found.html
+++ b/templates/error.html
@@ -4,9 +4,12 @@
 
 <main class="usa-section usa-content">
 
-<h1>Not Found</h1>
+{% if message %}
+    <h1>{{ message }}</h1>
+{% else %}
+    <h1>An error occurred.</h1>
+{% endif %}
 
 </main>
 
 {% endblock %}
-
diff --git a/templates/unauthenticated.html b/templates/unauthenticated.html
deleted file mode 100644
index 8fabbdf9..00000000
--- a/templates/unauthenticated.html
+++ /dev/null
@@ -1,12 +0,0 @@
-{% extends "error_base.html" %}
-
-{% block content %}
-
-<main class="usa-section usa-content">
-
-<h1>Log in Failed</h1>
-
-</main>
-
-{% endblock %}
-
diff --git a/tests/domain/test_users.py b/tests/domain/test_users.py
index 72917f5b..145e8f93 100644
--- a/tests/domain/test_users.py
+++ b/tests/domain/test_users.py
@@ -2,7 +2,7 @@ import pytest
 from uuid import uuid4
 
 from atst.domain.users import Users
-from atst.domain.exceptions import NotFoundError
+from atst.domain.exceptions import NotFoundError, AlreadyExistsError
 
 DOD_ID = "my_dod_id"
 
@@ -12,6 +12,12 @@ def test_create_user():
     assert user.atat_role.name == "developer"
 
 
+def test_create_user_with_existing_email():
+    Users.create(DOD_ID, "developer", email="thisusersemail@usersRus.com")
+    with pytest.raises(AlreadyExistsError):
+        Users.create(DOD_ID, "admin", email="thisusersemail@usersRus.com")
+
+
 def test_create_user_with_nonexistent_role():
     with pytest.raises(NotFoundError):
         Users.create(DOD_ID, "nonexistent")