Canvas app passes pac validate but Studio cannot open and player serves stale optimized package

Summary

A classic canvas app package imports and publishes successfully through the Power Apps package API. The exported live .msapp then passes both pac canvas unpack and pac canvas validate, but Power Apps Studio cannot open the app and the player continues serving an older optimized web package while showing: A new version of this app is coming. We'll let you know when it's available.

I realize this may cross the boundary between Power Apps Studio/player and Language Tooling, but the only local validation tools available report the package as valid. Filing here because the package/tooling roundtrip gives no indication of the issue before the Studio/web-package compiler failure.

Environment

• pac version failed: Command '['pac', '--version']' returned non-zero exit status 1.
• Darwin JNPR-MAC-KH9J9F 25.4.0 Darwin Kernel Version 25.4.0: Thu Mar 19 19:33:25 PDT 2026; root:xnu-12377.101.15~1/RELEASE_ARM64_T6041 arm64
• Source format version observed by pac canvas unpack: 0.24
• App type: classic canvas app, exported/imported .msapp
• App import/publish API status: HTTP 200
• App version after publish: 2026-05-27T09:18:58Z
• Last modified time after publish: 2026-05-27T09:19:04.406805Z
• Power Apps Studio error session ID: a4ef4528-6195-41b9-98ed-e6e5967de1b1

Expected behavior

A package that imports, publishes, exports, unpacks, and validates cleanly should either open in Studio and regenerate the player web package, or the local tooling should expose a validation error that predicts why Studio/web-package compilation will fail.

Actual behavior

• Import/publish succeeds via API.
• Exported live .msapp contains the expected new controls.
• pac canvas unpack emits no errors against the exported live .msapp.
• pac canvas validate emits no validation errors.
• Studio opens an Error opening app dialog with session ID a4ef4528-6195-41b9-98ed-e6e5967de1b1.
• Player still loads stale optimized content from content.powerapps.com/resource/app/jsims1hc2pt79/preloadindex.web.html with piv=1437890726 and shows the new version banner.

Full local validation logs

pac canvas unpack of exported live app

'pac canvas unpack' and 'pac canvas pack' are deprecated, and will be removed in a future release.
Unpack from /Users/mhickok/Documents/LRE-Workbench/output/powerapps-current-export-after-studio-error-20260527T092252Z/current-export.msapp --> /Users/mhickok/Documents/LRE-Workbench/output/powerapps-current-export-after-studio-error-20260527T092252Z/current-unpack
  source format version: 0.24

pac canvas validate of exported live app

Warning: canvas validate is in preview, and functionality is not guaranteed. Use extreme caution if using in a production environment. For more information see https://aka.ms/paccanvas

Additional retries on 2026-05-27

After further simplification of the generated formulas, the same package flow still succeeded locally and through import/publish, but Studio still failed and the player still served the same stale optimized web package.

• Later publish app version: 2026-05-27T09:58:08Z
• Later last modified time: 2026-05-27T09:58:17.7036109Z
• Later Studio error session ID: bc3561b6-831e-462b-bc1c-884e31a54e63
• Player stale package remained: content.powerapps.com/resource/app/jsims1hc2pt79/preloadindex.web.html with piv=1437890726
• App metadata kept returning performanceOptimizationEnabled: true even when the import package carried false in both top-level and nested app-definition metadata.

No source file or test is named. Start by reproducing the pac canvas unpack/validate flow against the exported .msapp, then compare its successful validation with the Studio error and stale player package described here. Done means the tooling either identifies the invalid condition before Studio fails or the package completes the documented roundtrip.