IDE Hangs on Startup

davrog20 · June 11, 2025, 9:43am

I notice there are quite a few entries for this, and each seem to have different causes, so I hope its ok to open my own topic.
I have tried installing both the MSI and exe versions, both result in the same initialising screen hanging.

Here is the diags result from running & ".\Arduino IDE", as per contributor requests from previous cases raised

PS C:\Program Files\Arduino IDE> & ".\Arduino IDE"
PS C:\Program Files\Arduino IDE>
Arduino IDE 2.3.6
Checking for frontend application configuration customizations. Module path: C:\Program Files\Arduino IDE\resources\app\lib\backend\electron-main.js, destination 'package.json': C:\Program Files\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}${appName}","files.autoSave":"afterDelay","editor.minimap.enabled":false,"editor.tabSize":2,"editor.scrollBeyondLastLine":false,"editor.quickSuggestions":{"other":false,"comments":false,"strings":false},"editor.maxTokenizationLineLength":500,"editor.bracketPairColorization.enabled":false,"breadcrumbs.enabled":false,"workbench.tree.renderIndentGuides":"none","explorer.compactFolders":false},"appVersion":"2.3.6","cliVersion":"1.2.0","buildDate":"2025-04-09T11:26:55.498Z"}
Starting backend process. PID: 10892
Showing main window early
Using browser-only version of superagent in non-browser environment
Configuration directory URI: 'file:///c%3A/Users/drr/.arduinoIDE'
Configuring to accept webviews on '^.+\.webview\..+$' hostname.
2025-06-11T09:19:01.076Z root INFO Backend u.initialize: 26.4 ms [Finished 0.606 s after backend start]
2025-06-11T09:19:01.077Z root INFO Backend Object.initialize: 24.8 ms [Finished 0.606 s after backend start]
2025-06-11T09:19:01.077Z root INFO Backend a.initialize: 1.5 ms [Finished 0.606 s after backend start]
2025-06-11T09:19:01.077Z root INFO Backend a.initialize: 1.3 ms [Finished 0.606 s after backend start]
2025-06-11T09:19:01.077Z root INFO Backend u.initialize: 1.6 ms [Finished 0.606 s after backend start]
2025-06-11T09:19:01.079Z root INFO Backend l.initialize: 26.3 ms [Finished 0.608 s after backend start]
2025-06-11T09:19:01.085Z root INFO configured all backend app contributions
2025-06-11T09:19:01.086Z root INFO Backend l.onStart: 1.0 ms [Finished 0.617 s after backend start]
2025-06-11T09:19:01.087Z root INFO Backend d.onStart: 0.1 ms [Finished 0.617 s after backend start]
2025-06-11T09:19:01.087Z root INFO Backend a.onStart: 0.4 ms [Finished 0.618 s after backend start]
2025-06-11T09:19:01.087Z config INFO >>> Initializing CLI configuration...
2025-06-11T09:19:01.087Z root INFO Backend x.onStart: 0.5 ms [Finished 0.618 s after backend start]
2025-06-11T09:19:01.087Z config INFO Loading CLI configuration from c:\Users\drr\.arduinoIDE\arduino-cli.yaml...
2025-06-11T09:19:01.087Z daemon INFO Starting daemon from C:\Program Files\Arduino IDE\resources\app\lib\backend\resources\arduino-cli.exe...
2025-06-11T09:19:01.087Z root INFO Backend w.onStart: 0.3 ms [Finished 0.619 s after backend start]
2025-06-11T09:19:01.087Z discovery-log INFO start
2025-06-11T09:19:01.087Z discovery-log INFO start new deferred
2025-06-11T09:19:01.087Z root INFO Backend v.onStart: 0.2 ms [Finished 0.619 s after backend start]
2025-06-11T09:19:01.087Z root INFO Backend a.onStart: 0.1 ms [Finished 0.619 s after backend start]
2025-06-11T09:19:01.198Z root WARN The local plugin referenced by local-dir:/c%3A/Users/drr/.arduinoIDE/plugins does not exist.
2025-06-11T09:19:01.198Z root WARN The local plugin referenced by local-dir:/c%3A/Users/drr/.arduinoIDE/deployedPlugins does not exist.
2025-06-11T09:19:01.198Z root WARN The local plugin referenced by local-dir:C:\Users\drr\.arduinoIDE\plugins does not exist.
2025-06-11T09:19:01.201Z root INFO Theia app listening on http://127.0.0.1:49900.
2025-06-11T09:19:01.202Z root INFO Finished starting backend application: 113.9 ms [Finished 0.733 s after backend start]
2025-06-11T09:19:01.414Z config INFO Loaded CLI configuration: {"board_manager":{"additional_urls":[]}}
2025-06-11T09:19:01.414Z config INFO Loading fallback CLI configuration to get 'directories.data' and 'directories.user'2025-06-11T09:19:01.424Z daemon INFO time="2025-06-11T10:19:01+01:00" level=info msg="arduino-cli version 1.2.0"
time="2025-06-11T10:19:01+01:00" level=info msg="Using config file: c:\\Users\\drr\\.arduinoIDE\\arduino-cli.yaml"
time="2025-06-11T10:19:01+01:00" level=info msg="Executing `arduino-cli daemon`"
Daemon is now listening on 127.0.0.1:49901
{"IP":"127.0.0.1","Port":"49901"}
2025-06-11T09:19:01.424Z daemon INFO Daemon is running.
2025-06-11T09:19:01.512Z daemon INFO time="2025-06-11T10:19:01+01:00" level=info msg="Updating index" url="https://downloads.arduino.cc/packages/package_index.tar.bz2"
2025-06-11T09:19:01.518Z daemon INFO time="2025-06-11T10:19:01+01:00" level=info msg="Starting download" url="https://downloads.arduino.cc/packages/package_index.tar.bz2"
2025-06-11T09:19:01.557Z root INFO Resolve plugins list: 467.1 ms [Finished 1.088 s after backend start]
2025-06-11T09:19:01.585Z config INFO Loaded fallback CLI configuration: {"directories":{"user":"C:\\Users\\drr\\Documents\\Arduino","data":"C:\\Users\\drr\\AppData\\Local\\Arduino15"}}
2025-06-11T09:19:01.585Z config INFO Merged CLI configuration with the fallback: {"directories":{"user":"C:\\Users\\drr\\Documents\\Arduino","data":"C:\\Users\\drr\\AppData\\Local\\Arduino15"},"board_manager":{"additional_urls":[]}}
2025-06-11T09:19:01.585Z config INFO Loaded the CLI configuration.
2025-06-11T09:19:01.585Z config INFO Mapped the CLI configuration: {"dataDirUri":"file:///c%3A/Users/drr/AppData/Local/Arduino15","sketchDirUri":"file:///c%3A/Users/drr/Documents/Arduino","additionalUrls":[],"network":"none","locale":"en"}
2025-06-11T09:19:01.585Z config INFO Validating the CLI configuration...
2025-06-11T09:19:01.585Z config INFO The CLI config is valid.
2025-06-11T09:19:01.585Z config INFO <<< Initialized the CLI configuration.
2025-06-11T09:19:02.480Z daemon INFO time="2025-06-11T10:19:02+01:00" level=info msg="Loading hardware from: C:\\Users\\drr\\AppData\\Local\\Arduino15\\packages"
time="2025-06-11T10:19:02+01:00" level=info msg="Loading libraries index file" index="C:\\Users\\drr\\AppData\\Local\\Arduino15\\library_index.json"
2025-06-11T09:19:02.486Z root ERROR Detected an error response during the gRPC core client initialization: code: 3, message: Some indexes could not be updated.
2025-06-11T09:19:02.487Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Loading index file: loading json index file C:\Users\drr\AppData\Local\Arduino15\package_index.json: open C:\Users\drr\AppData\Local\Arduino15\package_index.json: The system cannot find the file specified.
2025-06-11T09:19:02.489Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Error loading hardware platform: discovery builtin:serial-discovery not found
2025-06-11T09:19:02.489Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Error loading hardware platform: discovery builtin:mdns-discovery not found
2025-06-11T09:19:04.040Z root INFO creating connection for 1
2025-06-11T09:19:05.552Z daemon INFO time="2025-06-11T10:19:05+01:00" level=info msg="Adding libraries dir" dir="C:\\Users\\drr\\AppData\\Local\\Arduino15\\libraries" isSingleLibrary=false location=ide
time="2025-06-11T10:19:05+01:00" level=info msg="Adding libraries dir" dir="C:\\Users\\drr\\Documents\\Arduino\\libraries" isSingleLibrary=false location=user
2025-06-11T09:19:05.556Z 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:
[platform-index] - code: 9, message: Loading index file: loading json index file C:\Users\drr\AppData\Local\Arduino15\package_index.json: open C:\Users\drr\AppData\Local\Arduino15\package_index.json: The system cannot find the file specified.
[platform-index] - code: 9, message: Error loading hardware platform: discovery builtin:serial-discovery not found
[platform-index] - code: 9, message: Error loading hardware platform: discovery builtin:mdns-discovery not found

2025-06-11T09:19:05.559Z root WARN Frontend a.configure took longer than the expected maximum 100 milliseconds: 572.3 ms [Finished 4.343 s after frontend start]
2025-06-11T09:19:05.583Z daemon INFO time="2025-06-11T10:19:05+01:00" level=info msg="Updating index" url="https://downloads.arduino.cc/packages/package_index.tar.bz2"
time="2025-06-11T10:19:05+01:00" level=info msg="Starting download" url="https://downloads.arduino.cc/packages/package_index.tar.bz2"
2025-06-11T09:19:05.589Z root WARN A command editor.action.toggleStickyScroll is already registered.
2025-06-11T09:19:05.591Z root INFO core-client-provider [platform-index] Downloading index: package_index.tar.bz2

Opening channel for service path '/services/electron-window'.
Opening channel for service path '/services/ide-updater'.
2025-06-11T09:19:05.650Z root INFO Deploy plugins list: 4560.8 ms [Finished 5.182 s after backend start]
2025-06-11T09:19:06.280Z root INFO Start frontend contributions: 779.1 ms [Finished 4.455 s after frontend start]
2025-06-11T09:19:06.280Z root INFO Changed application state from 'init' to 'started_contributions'.
2025-06-11T09:19:06.280Z root INFO Changed application state from 'started_contributions' to 'attached_shell'.
2025-06-11T09:19:06.280Z root INFO >>> Restoring the layout state...
2025-06-11T09:19:06.287Z root INFO [a09be127-d045-429e-93b0-0b9b3fbb3ae7] Waiting for backend deployment: 621.9 ms [Finished 5.073 s after frontend start]
2025-06-11T09:19:06.290Z root ERROR Failed to update platform indexes. Error: 13 INTERNAL: Some indexes could not be updated.
    at t.callErrorFromStatus (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:3089094)
    at Object.onReceiveStatus (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6681994)
    at Object.onReceiveStatus (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:2571739)
    at C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:4307911
    at process.processTicksAndRejections (node:internal/process/task_queues:77:11)
for call at
    at s.makeServerStreamRequest (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6681761)
    at s.updateIndex (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:3088187)
    at C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6284829
    at C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6285177
    at new Promise (<anonymous>)
    at y.doUpdateIndex (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6285156)
    at y.updatePlatformIndex (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6284801)
    at y.updateIndex (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6284169)
    at y.initInstanceWithFallback (C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6282462)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
2025-06-11T09:19:06.416Z daemon INFO time="2025-06-11T10:19:06+01:00" level=info msg="Updating index" url="https://downloads.arduino.cc/packages/package_index.tar.bz2"
time="2025-06-11T10:19:06+01:00" level=info msg="Starting download" url="https://downloads.arduino.cc/packages/package_index.tar.bz2"
2025-06-11T09:19:06.735Z root INFO [hosted-plugin: 12424] PLUGIN_HOST(12424) starting instance
[Object: null prototype] {}
2025-06-11T09:19:06.736Z root ERROR Detected an error response during the gRPC core client initialization: code: 3, message: Some indexes could not be updated.
2025-06-11T09:19:06.736Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Loading index file: loading json index file C:\Users\drr\AppData\Local\Arduino15\package_index.json: open C:\Users\drr\AppData\Local\Arduino15\package_index.json: The system cannot find the file specified.
2025-06-11T09:19:06.736Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Error loading hardware platform: discovery builtin:serial-discovery not found
2025-06-11T09:19:06.736Z root ERROR Detected an error response during the gRPC core client initialization: code: 9, message: Error loading hardware platform: discovery builtin:mdns-discovery not found
2025-06-11T09:19:06.736Z daemon INFO time="2025-06-11T10:19:06+01:00" level=info msg="Loading hardware from: C:\\Users\\drr\\AppData\\Local\\Arduino15\\packages"
time="2025-06-11T10:19:06+01:00" level=info msg="Loading libraries index file" index="C:\\Users\\drr\\AppData\\Local\\Arduino15\\library_index.json"
2025-06-11T09:19:06.877Z daemon INFO time="2025-06-11T10:19:06+01:00" level=info msg="Adding libraries dir" dir="C:\\Users\\drr\\AppData\\Local\\Arduino15\\libraries" isSingleLibrary=false location=ide
2025-06-11T09:19:06.878Z 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:
[platform-index] - code: 9, message: Loading index file: loading json index file C:\Users\drr\AppData\Local\Arduino15\package_index.json: open C:\Users\drr\AppData\Local\Arduino15\package_index.json: The system cannot find the file specified.
[platform-index] - code: 9, message: Error loading hardware platform: discovery builtin:serial-discovery not found
[platform-index] - code: 9, message: Error loading hardware platform: discovery builtin:mdns-discovery not found

2025-06-11T09:19:06.878Z 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:
[platform-index] - code: 9, message: Loading index file: loading json index file C:\Users\drr\AppData\Local\Arduino15\package_index.json: open C:\Users\drr\AppData\Local\Arduino15\package_index.json: The system cannot find the file specified.
[platform-index] - code: 9, message: Error loading hardware platform: discovery builtin:serial-discovery not found
[platform-index] - code: 9, message: Error loading hardware platform: discovery builtin:mdns-discovery not found

    at C:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6283973
    at y.evaluateErrorStatus (C:\Program Files\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:\Program Files\Arduino IDE\resources\app\lib\backend\main.js:2:6283659)
2025-06-11T09:19:06.878Z daemon INFO time="2025-06-11T10:19:06+01:00" level=info msg="Adding libraries dir" dir="C:\\Users\\drr\\Documents\\Arduino\\libraries" isSingleLibrary=false location=user
2025-06-11T09:19:07.384Z root INFO [a09be127-d045-429e-93b0-0b9b3fbb3ae7] Sync of 23 plugins: 1102.3 ms [Finished 6.175 s after frontend start]

ptillisch · June 11, 2025, 9:57am

I think you were wise to do that. As you noticed, there are a variety distinct causes of the general symptom of Arduino IDE hanging on startup, each of which might have a completely different solution. It is difficult to support users who encounter that general symptom and then request assistance on an existing topic when the cause of their hang is different than that of others who posted on the topic.

On the first run after a fresh installation, Arduino IDE downloads some additional essential components from the Internet and installs them. If it can't install those components then the startup fails. So the computer must have access to the Internet on the first startup.

The errors indicate Arduino IDE is not able to access the Internet. If it is not already, please connect your computer to the Internet, close the Arduino IDE window, then start Arduino IDE again. This time it should start up successfully.

After that first run, an Internet connection is not required. However, there are some supplemental features such as "Library Manager" that have an inherent dependency on the Internet. Those features will not be usable while your computer is offline. But the essential functionality of editing, compiling, and uploading sketches will be available even without an Internet connection.

davrog20 · June 17, 2025, 10:41am

Hi thanks for that, and I suspected as much, as our firewall does block a lot of incoming traffic for security reasons.
Is there possibly an offline installer with all the supplementary download available within, do you know?

ptillisch · June 17, 2025, 11:01am

We don't provide such a thing. However, you could install Arduino IDE on another Windows computer which does have the necessary access to the Internet, start Arduino IDE to allow it to download the additional files, then transfer the files from that computer to the computer that is in the restricted network.

If that is something you are interested in, I'd be happy to provide instructions for transferring the file.

davrog20 · June 17, 2025, 11:57am

Hi - yes thanks, that would work for us, as we do have 'non-corporate machines we can use for this purpose.

ptillisch · June 17, 2025, 6:55pm

OK, great:

Install Arduino IDE on the "non-corporate" machine.
Start Arduino IDE.
Wait for Arduino IDE to start up fully, and for the installation processes that are indicated on the "Output" panel at the bottom of the Arduino IDE window to finish.
The previous step will automatically install the "Arduino AVR Boards" platform that adds support to Arduino IDE for the foundational boards like the UNO R3, Leonardo, Mega2560. If you want to work with other boards, it might be a good idea to install the Arduino boards platforms for those boards at this time in case it will not be possible to do so from the machine in the restricted network. You can do this by using Arduino IDE's "Boards Manager" feature:
https://docs.arduino.cc/software/ide-v2/tutorials/ide-v2-board-manager
Copy the folder at the following path on the "non-corporate" machine to the equivalent path on the machine in the restricted network:
```
C:\Users\<username>\AppData\Local\Arduino15\
```
(Where <username> is your Windows username)
- If looking for it with your file manager or command line, note that the AppData folder is hidden by default. On Windows "File Explorer", you can make it visible by opening the "View" menu, then checking the box next to "☐ Hidden items".

After that, try starting Arduino IDE on the machine in the restricted network again. Hopefully it will start up fully and work as expected this time.

As long as the essential additional files that are normally installed on the first run are present, Arduino IDE will have all its basic functionalities for writing, compiling, and uploading sketches to the Arduino board. However, you should be aware that some of the additional features do require Internet access:

Boards Manager
Library Manager
Firmware Updater
auto-updates for the Arduino IDE application

davrog20 · July 15, 2025, 8:01am

Thankyou for that - yes, it works! (well opens up now at least - reports a few subsequent 403 forbidden errors, but user confirmed working
Thanks!

davrog20 · July 15, 2025, 8:15am

(apologies for late response - I'd neglected to hit the send button weeks back! :D)

ptillisch · July 15, 2025, 10:56am

You are welcome. I'm glad it is working. Thanks for taking the time to post an update.

Regards, Per

system · January 11, 2026, 10:57am

This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.

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