React App Builder Sandbox Installs May Fail to Install Dependencies

Incident Report for Retool

Resolved

This incident is resolved. Images with the fix are out:

4.0.12-stable
4.43.0-edge

Our minimum release age for React app builder dependencies is 5 days, so this incident will self-resolve for any self-hosted deployments that don't upgrade on August 24th, by 7am PST. All currently affected self-hosted versions:

stable: 4.0.0 - 4.0.11
edge: 4.1, 4.9, 4.16, 4.19, 4.23, 4.27, 4.31, 4.35, 4.40
Posted Aug 20, 2026 - 23:20 UTC

Monitoring

Images with the fix are out:

4.0.12-stable
4.43.0-edge

Our minimum release age for React app builder dependencies is 5 days, so this incident will self-resolve for any self-hosted deployments that don't upgrade on August 24th, by 7am PST. All currently affected self-hosted versions:

stable: 4.0.0 - 4.0.11
edge: 4.1, 4.9, 4.16, 4.19, 4.23, 4.27, 4.31, 4.35, 4.40
Posted Aug 20, 2026 - 21:08 UTC

Update

This issue affects Retool version 4.0.0+ (stable and edge), specifically for 1) newly-created React apps, 2) new publishes of existing React apps, and 3) cold starts of sandboxes when editing existing React apps.

Existing published apps that do not get published after August 19th are unaffected.

Self-hosted customers can update to 4.43.0-edge to get an immediate fix. A patch to our stable release channel is coming soon.
Posted Aug 20, 2026 - 18:16 UTC

Identified

This issue no longer affects the React App Builder on Retool Cloud.

We have identified the issue for self-hosted, and are working on releasing images with a fix
Posted Aug 20, 2026 - 17:30 UTC

Investigating

Retool's app builder may fail to install and connect to a sandbox due to downstream dependency issues. This affects both Cloud and Self-Hosted Retool instances.
Posted Aug 20, 2026 - 17:26 UTC
This incident affected: New app builder and Self Hosted On-Premise.