"gulp serve" is returning workbench.html that i can not add the web part to

[mvcsharepointdev]

What type of issue is this?

Question

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Target SharePoint environment

SharePoint Online

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

• browser version
• SPFx version ---> 1.12.1
• Node.js version ---> 10.24.1
• etc

Issue description

I have developed an SPFx web part with this details:-

yo-rc.json for the project, is:-

 

{
  "@microsoft/generator-sharepoint": {
    "isCreatingSolution": true,
    "environment": "spo",
    "version": "1.12.1",
    "libraryName": "spfx-my-modal-popup",
    "libraryId": "616c9b54-d123-42d8-9942-9abb0fe4f46c",
    "packageManager": "npm",
    "isDomainIsolated": false,
    "componentType": "webpart"
  }
}

now i installed nvm to be able to run multiple node versions, here what i did so far:-

1. I install node version 10.24.1 , then i use it as follow :-

nvm use 10.24.1

2. i run :-
   gulp serve

The https://localhost:4321/temp/workbench.html opened but when i tried to add the web part by clicking on the + icon i will get this error inside the F12 developer tool:-

here is the full error:-

[1636842661379][PropertyPaneLoader] [SPLoaderError.loadComponentError]:

***Failed to load component "f9e737b7-f0df-4597-ba8c-3060f82380db" (SPPropertyPane). Original error: ***Failed to load URL 'https://localhost:4321/node_modules/@microsoft/sp-property-pane/dist/dist/sp-property-pane_en-us.js' for resource 'sp-property-pane' in component 'f9e737b7-f0df-4597-ba8c-3060f82380db' (SPPropertyPane). The file was not found in the server. Make sure that you are running 'gulp serve'.



***INNERERROR:

***Failed to load URL 'https://localhost:4321/node_modules/@microsoft/sp-property-pane/dist/dist/sp-property-pane_en-us.js' for resource 'sp-property-pane' in component 'f9e737b7-f0df-4597-ba8c-3060f82380db' (SPPropertyPane). The file was not found in the server. Make sure that you are running 'gulp serve'.

***CALLSTACK:

SPError@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:24443:24
SPLoaderError@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:42161:28
ff4n/ErrorBuilder</ErrorBuilder.buildErrorWithVerboseLog@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46155:21
ff4n/ErrorBuilder</ErrorBuilder.buildLoadComponentError@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46024:21
_loadComponentImpl/<@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45362:75
promise callback*_loadComponentImpl@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45361:8
_loadComponentRetryStrategy@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45299:12
_loadComponentRetryStrategy/<@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45309:20
promise callback*_loadComponentRetryStrategy@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45304:10
_loadComponentRetryStrategy/<@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45309:20
promise callback*_loadComponentRetryStrategy@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45304:10
loadComponent@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45281:55
++S4/SPRequireJsComponentLoader</SPRequireJsComponentLoader.prototype._loadComponentWithExecutor@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:41771:85
td2X/LoadComponentExecutor</LoadComponentExecutor.prototype.loadComponent@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46896:21
++S4/SPRequireJsComponentLoader</SPRequireJsComponentLoader.prototype.loadComponent@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:41742:44
Uk6p/BaseComponentLoader</BaseComponentLoader.prototype.loadComponentById@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:44816:25
KZU3/SPComponentLoader</SPComponentLoader.loadComponentById@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:43438:44
get@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:110639:99
set@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:16957:21
set@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:14989:13
CanvasToolboxHint/_this._handleClick@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/chunk.sp-canvas-edit_7833b0118fe685da1388.js:3982:17
callCallback@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75432:14
invokeGuardedCallbackDev@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75482:16
invokeGuardedCallback@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75539:31
invokeGuardedCallbackAndCatchFirstError@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75553:25
executeDispatch@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75844:42
executeDispatchesInOrder@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75866:20
executeDispatchesAndRelease@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75963:29
executeDispatchesAndReleaseTopLevel@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75971:10
forEachAccumulated@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75945:8
runEventsInBatch@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:76099:21
runExtractedEventsInBatch@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:76107:19
handleTopLevel@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:80109:30
batchedUpdates$1@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95687:12
batchedUpdates@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:77434:12
dispatchEvent@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:80188:19
interactiveUpdates$1/<@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95738:14
unstable_runWithPriority@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:97248:12
interactiveUpdates$1@https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95737:22
sp-webpart-workbench-assembly_default.js:26401:21
Uncaught (in promise) Error: ***Failed to load component "f9e737b7-f0df-4597-ba8c-3060f82380db" (SPPropertyPane). Original error: ***Failed to load URL 'https://localhost:4321/node_modules/@microsoft/sp-property-pane/dist/dist/sp-property-pane_en-us.js' for resource 'sp-property-pane' in component 'f9e737b7-f0df-4597-ba8c-3060f82380db' (SPPropertyPane). The file was not found in the server. Make sure that you are running 'gulp serve'.
    SPError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:24443
    SPLoaderError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:42161
    buildErrorWithVerboseLog https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46155
    buildLoadComponentError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46024
    _loadComponentImpl https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45362
    promise callback*_loadComponentImpl https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45361
    _loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45299
    _loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45309
    promise callback*_loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45304
    _loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45309
    promise callback*_loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45304
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45281
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46458
    _loadComponentImpl https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:43631
    promise callback*PypK/SystemJsFallbackLoader</SystemJsFallbackLoader.prototype._loadComponentImpl https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:43621
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46896
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:43617
    _loadComponentWithExecutor https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:41781
    promise callback*++S4/SPRequireJsComponentLoader</SPRequireJsComponentLoader.prototype._loadComponentWithExecutor https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:41777
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46896
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:41742
    loadComponentById https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:44816
    loadComponentById https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:43438
    get https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:110639
    set https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:16957
    set https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:14989
    _handleClick https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/chunk.sp-canvas-edit_7833b0118fe685da1388.js:3982
    callCallback https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75432
    invokeGuardedCallbackDev https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75482
    invokeGuardedCallback https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75539
    invokeGuardedCallbackAndCatchFirstError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75553
    executeDispatch https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75844
    executeDispatchesInOrder https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75866
    executeDispatchesAndRelease https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75963
    executeDispatchesAndReleaseTopLevel https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75971
    forEachAccumulated https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75945
    runEventsInBatch https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:76099
    runExtractedEventsInBatch https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:76107
    handleTopLevel https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:80109
    batchedUpdates$1 https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95687
    batchedUpdates https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:77434
    dispatchEvent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:80188
    1 https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95738
    unstable_runWithPriority https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:97248
    interactiveUpdates$1 https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95737
    interactiveUpdates https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:77453
    dispatchInteractiveEvent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:80165
sp-webpart-workbench-assembly_default.js:24430:28
Uncaught (in promise) Error: ***Failed to load component "f9e737b7-f0df-4597-ba8c-3060f82380db" (SPPropertyPane). Original error: ***Failed to load URL 'https://localhost:4321/node_modules/@microsoft/sp-property-pane/dist/dist/sp-property-pane_en-us.js' for resource 'sp-property-pane' in component 'f9e737b7-f0df-4597-ba8c-3060f82380db' (SPPropertyPane). The file was not found in the server. Make sure that you are running 'gulp serve'.
    SPError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:24443
    SPLoaderError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:42161
    buildErrorWithVerboseLog https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46155
    buildLoadComponentError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46024
    _loadComponentImpl https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45362
    promise callback*_loadComponentImpl https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45361
    _loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45299
    _loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45309
    promise callback*_loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45304
    _loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45309
    promise callback*_loadComponentRetryStrategy https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45304
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:45281
    _loadComponentWithExecutor https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:41771
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:46896
    loadComponent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:41742
    loadComponentById https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:44816
    loadComponentById https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:43438
    get https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:110639
    set https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:16957
    set https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:14989
    _handleClick https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/chunk.sp-canvas-edit_7833b0118fe685da1388.js:3982
    callCallback https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75432
    invokeGuardedCallbackDev https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75482
    invokeGuardedCallback https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75539
    invokeGuardedCallbackAndCatchFirstError https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75553
    executeDispatch https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75844
    executeDispatchesInOrder https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75866
    executeDispatchesAndRelease https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75963
    executeDispatchesAndReleaseTopLevel https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75971
    forEachAccumulated https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:75945
    runEventsInBatch https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:76099
    runExtractedEventsInBatch https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:76107
    handleTopLevel https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:80109
    batchedUpdates$1 https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95687
    batchedUpdates https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:77434
    dispatchEvent https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:80188
    1 https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95738
    unstable_runWithPriority https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:97248
    interactiveUpdates$1 https://localhost:4321/temp/workbench-packages/@microsoft_sp-webpart-workbench/local-workbench/sp-webpart-workbench-assembly_default.js:95737
s

Thank you for reporting this issue. We will be triaging your incoming issue as soon as possible.

[patmill]

You want to use Node 12, not Node 10. Release notes for 1.12.1 are here - https://docs.microsoft.com/en-us/sharepoint/dev/spfx/release-1.12.1

Also, does this file exist?

https://localhost:4321/node_modules/@microsoft/sp-property-pane/dist/dist/sp-property-pane_en-us.js

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