---
title: Configure CMS user interface
slug: cms-11/dev-docs/configuring-cms-user-interface
docTags: 
createdAt: 2026-07-22T19:45:17.341Z
---

## Iframe response timeout

If you get this message in edit view, you have hit the response timeout for the editing iframe:

*Preview Unavailable*

*Failed to load the preview within the given time constraints.*

The default time to load a preview is 15 seconds. You can increase it by adding `PreviewTimeout` in *appSettings.json*. The value should be in milliseconds.

To set the preview timeout to 20 seconds, add this configuration:

```xml
<appSettings>
  <!-- Set iframe timeout to 20 seconds -->
  <add key="episerver:ui:PreviewTimeout" value="20000" />
</appSettings
```

Optimizely added this timeout in the `EPiServer.CMS.UI` 10.2.0 package to solve a bug and make the iframe load more reliably.

## ApprovalStepRoleUserLimit configuration

If you are using large user groups in content approvals, there is a risk of performance issues (and unhappy users) due to the high number of notifications in the system. There is an `appSetting` called `ApprovalStepRoleUserLimit`, which triggers a validation warning when an administrator adds a group with members exceeding this setting. It will also limit the amount of notifications sent to the users in the group. The default setting is 100 users per group, but you can condigure it in this key:

```xml
<appSettings>
  <add key="episerver:ui:ApprovalStepRoleUserLimit" value="100" />
</appSettings>
```