Arduino IDE hangs on startup

Development Tools IDE 2.x
1

IDE is not opening, it just gets stuck on the loading menu.

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PS C:\Users\nolan\AppData\Local\Programs\Arduino IDE> & ".\Arduino IDE"
PS C:\Users\nolan\AppData\Local\Programs\Arduino IDE>
Arduino IDE 2.3.6
Checking for frontend application configuration customizations. Module path: C:\Users\nolan\AppData\Local\Programs\Arduino IDE\resources\app\lib\backend\electron-main.js, destination 'package.json': C:\Users\nolan\AppData\Local\Programs\Arduino IDE\resources\app\package.json
Setting 'theia.frontend.config.appVersion' application configuration value to: "2.3.6" (type of string)
Setting 'theia.frontend.config.cliVersion' application configuration value to: "1.2.0" (type of string)
Setting 'theia.frontend.config.buildDate' application configuration value to: "2025-04-09T11:26:55.498Z" (type of string)
Frontend application configuration after modifications: {"applicationName":"Arduino IDE","defaultTheme":{"light":"arduino-theme","dark":"arduino-theme-dark"},"defaultIconTheme":"none","electron":{"windowOptions":{},"showWindowEarly":true,"splashScreenOptions":{},"uriScheme":"arduino-ide"},"defaultLocale":"","validatePreferencesSchema":false,"reloadOnReconnect":true,"uriScheme":"theia","preferences":{"window.title":"${rootName}${activeEditorShort}${appName}","files.autoSave":"afterDelay","editor.minimap.enabled":false,"editor.tabSize":2,"editor.scrollBeyondLastLine":false,"editor.quickSuggestions":{"other":false,"comments":false,"strings":false},"editor.maxTokenizationLineLength":500,"editor.bracketPairColorization.enabled":false,"breadcrumbs.enabled":false,"workbench.tree.renderIndentGuides":"none","explorer.compactFolders":false},"appVersion":"2.3.6","cliVersion":"1.2.0","buildDate":"2025-04-09T11:26:55.498Z"}
Starting backend process. PID: 17572
Showing main window early
Using browser-only version of superagent in non-browser environment
Configuration directory URI: 'file:///c%3A/Users/nolan/.arduinoIDE'
Configuring to accept webviews on '^.+.webview..+$' hostname.
2025-11-13T17:22:49.141Z root INFO Backend u.initialize: 24.8 ms [Finished 0.510 s after backend start]
2025-11-13T17:22:49.141Z root INFO Backend Object.initialize: 21.7 ms [Finished 0.510 s after backend start]
2025-11-13T17:22:49.141Z root INFO Backend a.initialize: 1.4 ms [Finished 0.510 s after backend start]
2025-11-13T17:22:49.141Z root INFO Backend a.initialize: 1.2 ms [Finished 0.510 s after backend start]
2025-11-13T17:22:49.141Z root INFO Backend u.initialize: 1.4 ms [Finished 0.510 s after backend start]
2025-11-13T17:22:49.143Z root INFO Backend l.initialize: 22.6 ms [Finished 0.511 s after backend start]
2025-11-13T17:22:49.148Z root INFO configured all backend app contributions
2025-11-13T17:22:49.148Z root INFO Backend l.onStart: 0.9 ms [Finished 0.519 s after backend start]
2025-11-13T17:22:49.149Z root INFO Backend d.onStart: 0.1 ms [Finished 0.519 s after backend start]
2025-11-13T17:22:49.150Z root INFO Backend a.onStart: 0.3 ms [Finished 0.519 s after backend start]
2025-11-13T17:22:49.150Z config INFO >>> Initializing CLI configuration...
2025-11-13T17:22:49.150Z root INFO Backend x.onStart: 0.4 ms [Finished 0.519 s after backend start]
2025-11-13T17:22:49.150Z config INFO Loading CLI configuration from c:\Users\nolan.arduinoIDE\arduino-cli.yaml...
2025-11-13T17:22:49.150Z daemon INFO Starting daemon from C:\Users\nolan\AppData\Local\Programs\Arduino IDE\resources\app\lib\backend\resources\arduino-cli.exe...
2025-11-13T17:22:49.150Z root INFO Backend w.onStart: 0.6 ms [Finished 0.520 s after backend start]
2025-11-13T17:22:49.150Z discovery-log INFO start
2025-11-13T17:22:49.150Z discovery-log INFO start new deferred
2025-11-13T17:22:49.150Z root INFO Backend v.onStart: 0.2 ms [Finished 0.521 s after backend start]
2025-11-13T17:22:49.150Z root INFO Backend a.onStart: 0.1 ms [Finished 0.521 s after backend start]
2025-11-13T17:22:49.154Z root INFO Theia app listening on http://127.0.0.1:56516.
2025-11-13T17:22:49.155Z root INFO Finished starting backend application: 4.2 ms [Finished 0.525 s after backend start]
2025-11-13T17:22:49.168Z root WARN The local plugin referenced by local-dir:/c%3A/Users/nolan/.arduinoIDE/plugins does not exist.
2025-11-13T17:22:49.168Z root WARN The local plugin referenced by local-dir:/c%3A/Users/nolan/.arduinoIDE/deployedPlugins does not exist.
2025-11-13T17:22:49.169Z root WARN The local plugin referenced by local-dir:C:\Users\nolan.arduinoIDE\plugins does not exist.
2025-11-13T17:22:49.189Z config INFO Loaded CLI configuration: {"board_manager":{"additional_urls":[]}}
2025-11-13T17:22:49.189Z config INFO Loading fallback CLI configuration to get 'directories.data' and 'directories.user'
2025-11-13T17:22:49.242Z root INFO Resolve plugins list: 90.3 ms [Finished 0.612 s after backend start]
2025-11-13T17:22:49.258Z daemon INFO time="2025-11-13T10:22:49-07:00" level=info msg="arduino-cli version 1.2.0"
2025-11-13T17:22:49.260Z daemon INFO time="2025-11-13T10:22:49-07:00" level=info msg="Using config file: c:\Users\nolan\.arduinoIDE\arduino-cli.yaml"
time="2025-11-13T10:22:49-07:00" level=info msg="Executing arduino-cli daemon"
2025-11-13T17:22:49.273Z daemon INFO Daemon is now listening on 127.0.0.1:56519
{"IP":"127.0.0.1","Port":"56519"}
2025-11-13T17:22:49.273Z daemon INFO Daemon is running.
2025-11-13T17:22:49.279Z config INFO Loaded fallback CLI configuration: {"directories":{"user":"C:\Users\nolan\OneDrive\Documents\Arduino","data":"C:\Users\nolan\AppData\Local\Arduino15"}}
2025-11-13T17:22:49.279Z config INFO Merged CLI configuration with the fallback: {"directories":{"user":"C:\Users\nolan\OneDrive\Documents\Arduino","data":"C:\Users\nolan\AppData\Local\Arduino15"},"board_manager":{"additional_urls":[]}}
2025-11-13T17:22:49.279Z config INFO Loaded the CLI configuration.
2025-11-13T17:22:49.288Z config INFO Mapped the CLI configuration: {"dataDirUri":"file:///c%3A/Users/nolan/AppData/Local/Arduino15","sketchDirUri":"file:///c%3A/Users/nolan/OneDrive/Documents/Arduino","additionalUrls":[],"network":"none","locale":"en"}
2025-11-13T17:22:49.288Z config INFO Validating the CLI configuration...
2025-11-13T17:22:49.289Z config INFO The CLI config is valid.
2025-11-13T17:22:49.289Z config INFO <<< Initialized the CLI configuration.
2025-11-13T17:22:49.295Z daemon INFO time="2025-11-13T10:22:49-07:00" level=info msg="Starting download" url="https://downloads.arduino.cc/libraries/library_index.tar.bz2"
2025-11-13T17:22:49.651Z root INFO Deploy plugins list: 499.6 ms [Finished 1.021 s after backend start]
2025-11-13T17:22:56.777Z root ERROR Detected an error response during the gRPC core client initialization: code: 3, message: Error verifying signature: signature expired: is your system clock set correctly?
2025-11-13T17:22:56.786Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Checking signature" index="C:\Users\nolan\AppData\Local\Arduino15\package_index.json" signatureFile="C:\Users\nolan\AppData\Local\Arduino15\package_index.json.sig" trusted=true
2025-11-13T17:22:56.787Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loading hardware from: C:\Users\nolan\AppData\Local\Arduino15\packages"
2025-11-13T17:22:56.788Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loading package builtin from: C:\Users\nolan\AppData\Local\Arduino15\packages\builtin"
time="2025-11-13T10:22:56-07:00" level=info msg="Checking existence of 'tools' path: C:\Users\nolan\AppData\Local\Arduino15\packages\builtin\tools"
time="2025-11-13T10:22:56-07:00" level=info msg="Loading tools from dir: C:\Users\nolan\AppData\Local\Arduino15\packages\builtin\tools"
2025-11-13T17:22:56.788Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loaded tool" tool="builtin:ctags@5.8-arduino11"
2025-11-13T17:22:56.788Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loaded tool" tool="builtin:dfu-discovery@0.1.2"
2025-11-13T17:22:56.789Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loaded tool" tool="builtin:mdns-discovery@1.0.12"
2025-11-13T17:22:56.789Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loaded tool" tool="builtin:serial-discovery@1.4.3"
2025-11-13T17:22:56.789Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loaded tool" tool="builtin:serial-monitor@0.15.0"
2025-11-13T17:22:56.796Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Loading libraries index file" index="C:\Users\nolan\AppData\Local\Arduino15\library_index.json"
2025-11-13T17:22:56.797Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Adding libraries dir" dir="C:\Users\nolan\AppData\Local\Arduino15\libraries" isSingleLibrary=false location=ide
time="2025-11-13T10:22:56-07:00" level=info msg="Adding libraries dir" dir="C:\Users\nolan\OneDrive\Documents\Arduino\libraries" isSingleLibrary=false location=user
2025-11-13T17:22:56.797Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Loading index file: reading library_index.json: open C:\Users\nolan\AppData\Local\Arduino15\library_index.json: The system cannot find the file specified.
2025-11-13T17:22:56.800Z root ERROR The primary packages indexes are missing. Running indexes update before initializing the core gRPC client The index of the cores and libraries must be updated before initializing the core gRPC client.
The following problems were detected during the gRPC client initialization:
[library-index] - code: 9, message: Loading index file: reading library_index.json: open C:\Users\nolan\AppData\Local\Arduino15\library_index.json: The system cannot find the file specified.

2025-11-13T17:22:56.802Z daemon INFO time="2025-11-13T10:22:56-07:00" level=info msg="Starting download" url="https://downloads.arduino.cc/libraries/library_index.tar.bz2"
2025-11-13T17:22:56.803Z root INFO core-client-provider [library-index] Downloading index: library_index.tar.bz2

2025-11-13T17:23:04.358Z daemon INFO time="2025-11-13T10:23:04-07:00" level=info msg="Starting download" url="https://downloads.arduino.cc/libraries/library_index.tar.bz2"
2025-11-13T17:23:10.767Z root INFO creating connection for 1
2025-11-13T17:23:10.889Z root ERROR Detected an error response during the gRPC core client initialization: code: 3, message: Error verifying signature: signature expired: is your system clock set correctly?
2025-11-13T17:23:10.901Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Checking signature" index="C:\Users\nolan\AppData\Local\Arduino15\package_index.json" signatureFile="C:\Users\nolan\AppData\Local\Arduino15\package_index.json.sig" trusted=true
2025-11-13T17:23:10.902Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loading hardware from: C:\Users\nolan\AppData\Local\Arduino15\packages"
2025-11-13T17:23:10.903Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loading package builtin from: C:\Users\nolan\AppData\Local\Arduino15\packages\builtin"
2025-11-13T17:23:10.903Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Checking existence of 'tools' path: C:\Users\nolan\AppData\Local\Arduino15\packages\builtin\tools"
time="2025-11-13T10:23:10-07:00" level=info msg="Loading tools from dir: C:\Users\nolan\AppData\Local\Arduino15\packages\builtin\tools"
2025-11-13T17:23:10.903Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loaded tool" tool="builtin:ctags@5.8-arduino11"
2025-11-13T17:23:10.904Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loaded tool" tool="builtin:dfu-discovery@0.1.2"
2025-11-13T17:23:10.904Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loaded tool" tool="builtin:mdns-discovery@1.0.12"
2025-11-13T17:23:10.904Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loaded tool" tool="builtin:serial-discovery@1.4.3"
2025-11-13T17:23:10.904Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loaded tool" tool="builtin:serial-monitor@0.15.0"
2025-11-13T17:23:10.921Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Loading libraries index file" index="C:\Users\nolan\AppData\Local\Arduino15\library_index.json"
2025-11-13T17:23:10.921Z daemon INFO time="2025-11-13T10:23:10-07:00" level=info msg="Adding libraries dir" dir="C:\Users\nolan\AppData\Local\Arduino15\libraries" isSingleLibrary=false location=ide
time="2025-11-13T10:23:10-07:00" level=info msg="Adding libraries dir" dir="C:\Users\nolan\OneDrive\Documents\Arduino\libraries" isSingleLibrary=false location=user
2025-11-13T17:23:10.921Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Loading index file: reading library_index.json: open C:\Users\nolan\AppData\Local\Arduino15\library_index.json: The system cannot find the file specified.
2025-11-13T17:23:10.922Z root ERROR Uncaught Exception: Error: The index of the cores and libraries must be updated before initializing the core gRPC client.
The following problems were detected during the gRPC client initialization:
[library-index] - code: 9, message: Loading index file: reading library_index.json: open C:\Users\nolan\AppData\Local\Arduino15\library_index.json: The system cannot find the file specified.

2025-11-13T17:23:10.922Z root ERROR Error: The index of the cores and libraries must be updated before initializing the core gRPC client.
The following problems were detected during the gRPC client initialization:
[library-index] - code: 9, message: Loading index file: reading library_index.json: open C:\Users\nolan\AppData\Local\Arduino15\library_index.json: The system cannot find the file specified.

at C:\Users\nolan\AppData\Local\Programs\Arduino IDE\resources\app\lib\backend\main.js:2:6283973
at y.evaluateErrorStatus (C:\Users\nolan\AppData\Local\Programs\Arduino IDE\resources\app\lib\backend\main.js:2:6283989)
at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
at async a.<anonymous> (C:\Users\nolan\AppData\Local\Programs\Arduino IDE\resources\app\lib\backend\main.js:2:6283659)

2025-11-13T17:23:11.586Z root WARN Frontend a.configure took longer than the expected maximum 100 milliseconds: 110.2 ms [Finished 22.423 s after frontend start]
2025-11-13T17:23:11.621Z root WARN A command editor.action.toggleStickyScroll is already registered.
Opening channel for service path '/services/electron-window'.
Opening channel for service path '/services/ide-updater'.
2025-11-13T17:23:11.743Z root INFO Start frontend contributions: 319.6 ms [Finished 22.568 s after frontend start]
2025-11-13T17:23:11.744Z root INFO Changed application state from 'init' to 'started_contributions'.
2025-11-13T17:23:11.760Z root INFO Changed application state from 'started_contributions' to 'attached_shell'.
2025-11-13T17:23:11.760Z root INFO >>> Restoring the layout state...
2025-11-13T17:23:11.797Z root INFO [3c71ac52-9f5a-4937-9c98-69f68f59057d] Waiting for backend deployment: 69.4 ms [Finished 22.631 s after frontend start]
2025-11-13T17:23:12.346Z root INFO [hosted-plugin: 1312] PLUGIN_HOST(1312) starting instance
[Object: null prototype] {}
2025-11-13T17:23:12.790Z root INFO [3c71ac52-9f5a-4937-9c98-69f68f59057d] Sync of 23 plugins: 998.0 ms [Finished 23.629 s after frontend start]

2

In the future post the verbose error log in code tags.
A quick scan shows some missing components, are you an admin on your PC?
There may also be an internet access issue and a system clock issue.
You will need to get the clock set correctly, ensure full internet access and use an admin id (sorry I don;t know that part as I drive a Mac)

3

Hi @nbrod13.

The cause of the problem is that your system time is incorrect. You can fix it by syncing the system time. I'll provide instructions you can follow to do that:

  1. Right click the Windows Start icon (⊞) on the taskbar.
    A context menu will open.
  2. Select "Settings" from the context menu.
    Windows "Settings" will open.
  3. Select "Time & language" from the navigation panel on the left side of the window.
  4. Select "Date & time" from the list at the right side of the Settings window.
    The "Date & time" settings section will expand.
  5. Click the "Sync now" button that is located under the "Additional settings" section of the window.
  6. Wait for the syncing process to finish.
  7. Close any Arduino IDE windows that are open.
  8. Start Arduino IDE again, as usual.
    ⓘ It is not required to start the IDE from the PowerShell terminal this time.

This time Arduino IDE should start up fully and work as expected.

4

Thank you both, syncing the system time fixed it.

5

You are welcome. I'm glad it is working now.

Regards, Per