Salesforce Sandbox Preview Instructions

Publish Date: Mar 3, 2026

Description

Summer '26 is coming with lots of new features. Use your sandbox to get early access to new features and test your configurations before the production upgrade.

The sandbox preview window for Summer '26 begins May 8, 2026. You must have an active sandbox on a preview instance by May 7, 2026 (the day before sandbox preview) to take advantage of the preview.

Here’s how... First, decide whether you want to:

Keep one or more of your sandboxes on the current Spring ’26 release version, or,
Try the next major release, Summer '26 version, in your sandbox(es).

After you decide:

Check if the Release Type of the sandbox is preview (upgrade) or non-preview (no upgrade), and
Determine if you need to refresh and when, based on the cutoff date of May 7, 2026.

Usually, no action is required because your sandbox is already on a preview instance.

How Does Sandbox Preview Work?

The sandbox preview is a 6-week window ahead of a major Salesforce release when all preview sandboxes are upgraded to the next major Salesforce release. It’s your first chance to test your configurations on the new release.

Sandboxes are updated in groups based on the instance where they’re located. All sandboxes on a preview instance get upgraded together, and all sandboxes on non-preview instances remain on the current release. The only way to change the upgrade status of a sandbox is to move it to another instance by refreshing it. If you want to move it to a preview instance, you must do so before the cutoff date.

Between now and May 7, 2026, we route all sandbox requests to preview instances. If your sandbox request is complete in time, we upgrade it to Summer '26.

On May 9, 2026, we reset all incomplete sandbox requests to a non-preview instance. All pending and new sandbox requests are routed to non-preview instances until your production instance is upgraded to Summer '26. We can create sandboxes only on the same major release version of Salesforce as production.

For the Summer '26 Release, we upgrade the preview instances to Summer '26 on May 8 and May 9, 2026, and non-preview instances to Summer '26 on June 12 and June 13, 2026.Follow the basic process below if you want your sandbox to participate in the Spring '26 preview.

1. Find your sandbox details.
In production, from Setup, in the Quick Find box, enter Sandbox, and then select Sandbox. Use the Release Type column to determine if your sandbox is on a preview or non-preview instance.

You can also use the Sandbox Preview Guide to determine if each of your sandboxes is on a preview or non-preview instance. Enter your sandbox instance name(s). The guide tells you if it’s preview or non-preview and what to do to either move to the next release (Summer '26) or stay on the current release (Spring '26). You can also check multiple sandboxes and view the full list of preview and non-preview instances.

2. Understand the cutoff date.

Every release, we give you a cutoff date for sandbox refresh completions, and usually, it’s the day before the preview starts. For Summer '26, the cutoff date is May 7, 2026. Any sandbox created after the cutoff isn’t a preview sandbox. If you have a sandbox on a preview instance and refresh it after the cutoff, your sandbox is routed to a non-preview instance and reverts to Spring '26.

Resolution

Should I Refresh my Sandbox?

Here are the most common scenarios:

It’s important to plan ahead. The popularity of the sandbox preview program often means backlogs in sandbox create and refresh requests, especially closer to the cutoff date. Remember, if it’s a full sandbox it can take some time to copy.

All incomplete sandboxes are reset to a non-preview instance before the sandbox preview starts on May 8, 2026, so we recommend that you request your sandbox at least a week before the deadline to improve your chances of getting a completed sandbox on a preview instance.

We aim to process each request on time, but we can’t guarantee the completion of your sandbox before the deadline.

I Want to Create a New Sandbox — What Are My Options?

Create a new sandbox that goes to a preview instance and gets the Summer '26 preview

Create a new sandbox that goes to a non-preview instance and stays on Spring '26

Submit your sandbox request well ahead of the 6:00 PM PT cutoff on May 7, 2026 (01:00 UTC on May 8, 2026) so that the sandbox copy is completed before the sandbox release.

Plan ahead. If you submit your request too close to the deadline and the copy isn’t completed, or if your request is after the deadline, your Sandbox is built on a non-preview instance.

Wait to submit your request to create a sandbox until after 6:00 PM PT on May 9, 2026 (01:00 UTC on May 10, 2026). If you submit your request before then, your Sandbox can be built on a Preview Instance.

I Have a Sandbox — What Are My Options?

If the Release Type of your sandbox is:

You want to try Summer '26 in your sandbox

You want the sandbox on Spring '26

Preview

No action needed. Your sandbox is already on a preview instance and gets upgraded to Summer '26 on May 8, 2026.

If you must refresh your sandbox for other reasons, do so well in advance of 6:00 PM PT on May 7, 2026 (01:00 UTC on May 8, 2026) to make sure that your sandbox is completed before the cutoff date.

If you refresh your sandbox after the deadline or your sandbox isn’t completed in time, it is built on a non-preview instance.

Refresh to a non-preview instance after the cutoff date to keep your sandbox on Spring '26.

To do so, wait to refresh after 6:00 PM PT on May 7, 2026 (1:00 UTC on May 8, 2026).

If you refresh your sandbox sooner, it can be built on a Preview Instance.

Refreshing a sandbox deletes it and recreates it as a new copy of production. Be sure to save any configurations or data unique to the sandbox elsewhere before refreshing it.

Non-Preview

Your sandbox is on a non-preview instance.

Refresh it between now and 6:00 PM PT on May 7, 2026 (01:00 UTC on May 8, 2026) to try out Summer '26.

If you refresh your sandbox after the deadline or your Sandbox isn’t completed in time, it is built on a non-preview instance.

No action is needed because your sandbox is on a non-preview instance and stays on Spring '26.

If you must refresh your sandbox for other reasons, wait to refresh it after 6:00 PM PT on May 7, 2026 (1:00 UTC on May 8, 2026) to remain on a non-preview instance.

Note: If you decide to keep your sandbox on the current Spring '26 release, your sandbox isn’t upgraded to Summer '26 until June 12, 2026, or June 13, 2026.

I Have a Sandbox That I Want to Clone - What Are My Options?

Before the sandbox preview window	Sandbox clone requests are routed to a preview instance until 6:00 PM PT on May 7, 2026 (01:00 UTC on May 8, 2026)
During the sandbox preview window	From 6:00 PM PT on May 7, 2026 (01:00 UTC May 8, 2026) through June 13, 2026, we process sandbox clone requests on the same release version of Salesforce as the sandbox being cloned.

AppExchange Preview Instructions

Use this chart if you plan to upload or install one or more AppExchange packages using your sandboxes during the sandbox preview window.

	You can upload AppExchange Packages:	You can install AppExchange Packages:	You can’t install AppExchange Packages
Before the sandbox preview window Anytime until sandbox preview starts on May 8, 2026	From your Spring '26 production or sandbox instance	To any Spring ‘26 production or sandbox instance
During the sandbox preview window From May 8, 2026, through June 12, 2026	From your Spring '26 production or sandbox instance	To any Spring ‘26 production or sandbox instance
	From your Summer '26 sandbox instance	To any Summer '26 production or sandbox instance	To any Summer '26 production or sandbox instance
After the sandbox preview window Any time after June 13, 2026	From your Summer '26 production or sandbox instance	To any Summer '26 production or sandbox instance

If you have any questions or need assistance about your sandbox options and the Summer '26 release, refer to Salesforce Help.

Resources

Get Early Access with the Sandbox Preview Unit | Salesforce Trailhead

Demystifying the Sandbox Preview | Video

Sandbox Preview Guide

Knowledge Article Number

000391927

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