ConcurrentModificationException: Schema is currently being altered, please wait until that is complete.

[TimmyAA]

Environment information

> npx ampx info
System:
  OS: Windows 11 10.0.22631
  CPU: (16) x64 11th Gen Intel(R) Core(TM) i7-11800H @ 2.30GHz
  Memory: 33.05 GB / 63.77 GB
Binaries:
  Node: 20.18.2 - C:\Program Files\nodejs\node.EXE
  Yarn: undefined - undefined
  npm: 10.8.2 - C:\Program Files\nodejs\npm.CMD
  pnpm: undefined - undefined
NPM Packages:
  @aws-amplify/auth-construct: 1.6.0
  @aws-amplify/backend: 1.14.0
  @aws-amplify/backend-auth: 1.5.0
  @aws-amplify/backend-cli: 1.4.8
  @aws-amplify/backend-data: 1.4.0
  @aws-amplify/backend-deployer: 1.1.15
  @aws-amplify/backend-function: 1.12.1
  @aws-amplify/backend-output-schemas: 1.4.0
  @aws-amplify/backend-output-storage: 1.1.4
  @aws-amplify/backend-secret: 1.1.5
  @aws-amplify/backend-storage: 1.2.4
  @aws-amplify/cli-core: 1.2.3
  @aws-amplify/client-config: 1.5.5
  @aws-amplify/deployed-backend-client: 1.5.0
  @aws-amplify/form-generator: 1.0.3
  @aws-amplify/model-generator: 1.0.12
  @aws-amplify/platform-core: 1.6.0
  @aws-amplify/plugin-types: 1.8.0
  @aws-amplify/sandbox: 1.2.11
  @aws-amplify/schema-generator: 1.2.7
  aws-amplify: 6.11.0
  aws-cdk: 2.173.2
  aws-cdk-lib: 2.173.2
  typescript: 5.7.2
No AWS environment variables
No CDK environment variables

Describe the bug

This error keeps coming up in sandbox (from windows) when making minor changes, like adding a field to a data model...
...failed: ConcurrentModificationException: Schema is currently being altered, please wait until that is complete.

The CloudFormation stack in console indicates "UPDATE_COMPLETE"

The only workaround that I've found is to run the sandbox with the changes from Ubuntu, then once complete, start the sandbox again in Windows

I did notice that when I save resource.ts, There is a double trigger on the file...

[Sandbox] Watching for file changes...
File written: amplify_outputs.json
[Sandbox] Triggered due to a file update event: \amplify\data\resource.ts
[Sandbox] Triggered due to a file update event: \amplify\data\resource.ts
[Sandbox] Previous deployment is still in progress. Will queue for another deployment after this one finishes
...
Error: ❌ d295 failed: ConcurrentModificationException: Schema is currently being altered, please wait until that is complete.

Caused By: ❌ d295 failed: ConcurrentModificationException: Schema is currently being altered, please wait until that is complete.

Reproduction steps

Adding a field to a data model.

[ykethan]

Hey,👋 thanks for raising this! I'm going to transfer this over to our data repository for better assistance 🙂

[AnilMaktala]

Hey @TimmyAA, Can you check your open terminals to see if you are running multiple sandbox instances?

[TimmyAA]

Hey @TimmyAA, Can you check your open terminals to see if you are running multiple sandbox instances?

Hi @AnilMaktala, 2 terminals open, one running 'npx ampx sandbox' and other running 'quasar dev'

[AnilMaktala]

@TimmyAA Thanks for checking. Do you have multiple stacks in your app? Also, what change in the resource.ts file triggered this issue?

[TimmyAA]

@TimmyAA Thanks for checking. Do you have multiple stacks in your app? Also, what change in the resource.ts file triggered this issue?

Single stack.
I added the 'signature' field to the model...

  SCResponses: a
    .model({
      id: a.id().required(),
...
      signature: a.string().required(),
...
      deletedAt: a.string(),
      deleted: a.boolean().default(false),
    })

The only thing that looked suspicious was this double trigger on a single save...

[Sandbox] Watching for file changes...
File written: amplify_outputs.json
[Sandbox] Triggered due to a file update event: \amplify\data\resource.ts
[Sandbox] Triggered due to a file update event: \amplify\data\resource.ts
[Sandbox] Previous deployment is still in progress. Will queue for another deployment after this one finishes

I may try not letting npx ampx sandbox watch for file changes and just run it after I change something in the stack
Or is there a local state file that gets out of sync, maybe caused by this double trigger

[TimmyAA]

Didn't work... added a new fields to a model while 'npx ampx sandbox' wasn't running. Then started it, same error.

...failed: ConcurrentModificationException: Schema is currently being altered, please wait until that is complete.

[AnilMaktala]

Hey @TimmyAA, Interesting! Are you on Discord by any chance?

[nat-jones]

Experiencing the same issue. Is there an update on this?

[TimmyAA]

No progress, but more information...
authorization changes on data resource work fine
storage resource changes work too

Just data model additions are a problem.

[AnilMaktala]

hi @TimmyAA, Thanks for additional detials. I am unable to reproduce the issue on my end. To rule out any sandbox-specific problems, could you please try running the sandbox with a new identifier and share the results?

`npx ampx sandbox --identifier somename'