web_pixel_extension deploy fails: "Only one script can be uploaded at a time" (appVersionCreate) — regression, blocking release

Shopify CLI and Libraries
1

I have reproduced the issue on the latest CLI version.

Yes, I am on the latest version

I have searched existing posts and this report is not a duplicate.

Yes, this isn’t a duplicate

In which of these areas are you experiencing a problem?

App

Expected behavior

shopify app deploy should create a new app version that includes the web_pixel_extension.

Actual behavior

Deploy fails at the appVersionCreate mutation with “Version couldn’t be created. / Only one script can be uploaded at a time” — even for a single web_pixel_extension, alone, on a brand-new app. A theme app extension deploys fine on the same app.

This is a regression: the identical source deployed successfully 8 times through 2026-05-15, and now fails on both our existing app and a freshly created one. Reverting our working tree to that exact known-good source and redeploying today still fails — so nothing changed on our end.

Reproduction steps

  1. Have an app that contains a web_pixel_extension.
  2. Run shopify app deploy.
  3. It fails at appVersionCreate: “Only one script can be uploaded at a time”.

Isolation on a brand-new app (first deploys):

extensions/ contains Result
web_pixel_extension only :cross_mark: Only one script can be uploaded at a time
theme app extension only :white_check_mark: deploys fine
both :cross_mark: same error

The web pixel fails ALONE — so it’s not a theme+pixel combo or app-specific state. In a run where the theme was already registered, adding only the web pixel (cmd_deploy_confirm_new_registrations: 1) still fails.

Ruled out: our code (known-good source fails), duplicate extension (dashboard shows 1 pixel + 1 theme), CLI version (fails on 3.94.3 and 4.5.2), the combo (pixel fails alone), stuck app state (brand-new app fails identically).

Verbose output

mediascale-pixel │ Bundling UI extension mediascale-pixel...
mediascale-pixel │ mediascale-pixel successfully built in 93ms
mediascale-embed │ Bundling theme extension mediascale-embed...
Running validation ...
Releasing an app version ...

# appVersionCreate mutation variables (sourceUrl trimmed):
{ "appId": "gid://shopify/App/399310225409",
  "version": { "sourceUrl": ".../partners-extensions-scripts-bucket/.../source.br" } }

# Response:
╭─ error ─╮
│ Version couldn't be created.
│ Only one script can be uploaded at a time
╰─╯

# From the analytics event:
"cli_version": "4.5.2"
"app_extensions_breakdown": {"web_pixel_extension":1,"theme":1}
"cmd_deploy_confirm_new_registrations": 1
"cmd_all_last_graphql_request_id": "98c288f9-0eb6-42bd-8a46-9704ed6ce15e-1784353981"
"request_ids": [
  "670671d0-e1ea-4991-a791-f632270255bd-1784353980",   # CreateAssetURL
  "98c288f9-0eb6-42bd-8a46-9704ed6ce15e-1784353981"    # appVersionCreate (failing)
]
"error_message": "Version couldn't be created."
"success": false

# For staff: the CLI logs only the appVersionCreate response headers, not the body,
# so userErrors (code/field) never surface. Please check the server-side response for
# request id 98c288f9-0eb6-42bd-8a46-9704ed6ce15e-1784353981 (app 399310225409).

Operating system

macOS (Apple Silicon / arm64)

CLI version

4.5.2

Shell

zsh

Nodejs version

22.18.0

What language and version are you using in your application?

JavaScript