An error occurred while executing Hermes command... Vega 0.21 & 0.22

Vega Open Beta Bug Reports
1

bug_logs.txt (5.7 KB)

:backhand_index_pointing_right: Bug Description

1. Summary

Provide a brief description of the bug in the SDK and its impact on app functionality.

When attempting to build our project we are seeing an error

An error occurred while executing Hermes command /Users/[userName]/vega/sdk/0.22.5875/packages/VegaUIReact-Hermes/VegaUIReact-Hermes-0.72.x_vodka.219616.0/AL2_x86_64/DEV.STD.PTHREAD/build/universal-Darwin/bin/hermesc,--emit-binary,-out,/Users/[userName]/Desktop/code/[project]/build/lib/rn-bundles/Release/index.hermes.bundle,/Users/[userName]/Desktop/code/[project]/build/lib/rn-bundles/Release/86a8cabff3eca67162980c1ff04438128e42e8abe4b575029cfd0beef9bf63ac.bundle,-O,-w: /Users/[userName]/Desktop/code/[project]/build/lib/rn-bundles/Release/86a8cabff3eca67162980c1ff04438128e42e8abe4b575029cfd0beef9bf63ac.bundle:225088:49: error: ';' expected
undefinedif (msg instanceof UpdateExperiment_1) { ^.

App Name: Philo
App Link on Amazon Appstore (found through Developer Console → Actions column in App List → View on Amazon.com): Philo: Live TV, Movies, Shows and Free Channels - App on Amazon Appstore

Bug Severity
Select one that applies

  • Impacts operation of app
  • Blocks current development
  • Improvement suggestion
  • Issue with documentation (If selected, please share the doc link and describe the issue)
  • Other

2. Steps to Reproduce

  1. use npm run build:release to build app

3. Observed Behavior

Explain what actually happened, noting any discrepancies or malfunctions.

The build starts but errors and does not finish

4. Expected Behavior

Describe what you expected the SDK to do under normal operation.

I expect a build folder with build files of the project in it

4.a Possible Root Cause & Temporary Workaround

Fill out anything you have tried. If you don’t know, N/A is acceptable

Haven't found one yet

5. Logs or crash report

(Please make sure to provide relevant logs as attachment)
bug_logs.txt (5.7 KB)

6. Environment

Please fill out the fields related to your bug below:

  • SDK Version: 0.22.5875 also seen with 0.21.**** as of Monday (2/2/26)
  • App State: BUILD
  • OS Information: Not on the device

:backhand_index_pointing_right: Additional Context

Any Additional Context you would like to provide?
Add any other relevant information, such as recent updates to the SDK, dependencies, or device OS that may affect the bug.

This started on Monday (02/02/26) with the same build that was working Friday (01/30/26)
3

The bug oddly went away after creating a build on the simulator (Vega virtual device)

4

Hi @Tony

Thank you for the detailed bug report on the Hermes compilation error.

I’m glad to hear the issue resolved itself after creating a build on the Vega Virtual Device. This suggests there may have been a cached or corrupted intermediate build artifact that was cleared during the simulator build process.

For future reference, if you encounter similar Hermes compilation errors, here are some troubleshooting steps that may help:

  1. Clean the build directory: Remove the build/ folder and rebuild
  2. Clear Metro bundler cache: npm start – --reset-cache
  3. Verify node_modules integrity: Delete node_modules/ and reinstall dependencies
  4. Build on the simulator first: As you discovered, this can help clear stale artifacts

The error message you encountered (‘;’ expected undefinedif (msg instanceof UpdateExperiment_1)) suggests the bundler may have generated malformed JavaScript, which could indicate a transient issue with the build pipeline or cached state.

Feel free to reach back to me if you have any questions or run into any issues!

Thanks for helping us improve the Vega platform.

Warm regards,
Aishwarya

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