Arduino IDE is broken [Windows]

[adguard-bot]

Issue URL (Incorrect Blocking)

https://www.arduino.cc/en/software/

Comment

Affected application: Arduino IDE 2.3.10

Environment:

OS: Windows
AdGuard for Windows with SocketFilter / network filtering enabled
Filtering mode: system-wide (traffic routed through AdGuard)

Summary:
When AdGuard for Windows is running with the SocketFilter active, Arduino IDE 2.3.10 hangs indefinitely on its splash/loading screen and never finishes starting. The IDE works normally as soon as AdGuard is stopped, or when its traffic is excluded from AdGuard's filtering.

Steps to reproduce:

Have AdGuard for Windows running with SocketFilter / filtering enabled.
Start Arduino IDE 2.3.10.
Observe that the IDE stays on the splash screen and does not load.

Expected behavior:
Arduino IDE starts normally; its internal services are reachable via localhost.

Actual behavior:
The IDE hangs on the splash screen. Reinstalling the IDE and resetting its configuration folders (.arduinoIDE15, Arduino15) does not help. Stopping AdGuard — or excluding the IDE / its localhost traffic from filtering — lets the IDE start immediately.

Root cause (observed in AdGuard log):
Arduino IDE 2.x communicates between its frontend and internal backend services entirely over loopback (localhost). The AdGuard filtering log shows these local connections being intercepted and filtered:

http://localhost:65153/cc.arduino.cli.commands.v1.ArduinoCoreService/Create
http://localhost:65153/cc.arduino.cli.commands.v1.ArduinoCoreService/Init
numerous http://localhost:65152/socket.io/?EIO=4&transport=polling&... requests
ws://localhost:65152/socket.io/?EIO=4&transport=websocket&...

Several of these requests are marked "7 rules applied" / "Privacy", which indicates AdGuard is actively acting on the IDE's loopback traffic. Because the IDE waits for these local service responses during startup, the interference causes it to hang before the UI loads.

Workaround (confirmed working):

Stopping AdGuard, or
Excluding Arduino IDE from AdGuard filtering, or
Not routing the IDE's traffic through AdGuard.

Screenshots

Screenshot 1

Screenshot 1 with AdGuard disabled

System configuration

Information	Value
AdGuard product:	AdGuard for Windows v8.0.5570
System version:	Microsoft Windows NT 10.0.26200.0
Browser:	-
License type:	paid
AdGuard driver:	TDI
Filters:	Ad Blocking: AdGuard Base filter Privacy: AdGuard Tracking Protection filter Annoyances: AdGuard Cookie Notices filter, AdGuard Popups filter, AdGuard Mobile App Banners filter, AdGuard Other Annoyances filter, AdGuard Widgets filter Language-specific: AdGuard German filter
Custom filters:	User rules (url: none)
Tracking protection:	General: Block trackers, Send Do-Not-Track header Windows Tracking: Disable Windows Telemetry, Turn off Advertising ID, Disable Windows Recall Miscellaneous: Remove X-Client-Data header from HTTP requests
DNS filtering:	disabled
Browsing Security:	enabled
Browsing Security statistics:	disabled
Userscripts:	AdGuard Extra (url: https://userscripts.adtidy.org/release/adguard-extra/1.0/adguard-extra.user.js) AdGuard Popup Blocker (url: https://userscripts.adtidy.org/release/popup-blocker/2.5/popupblocker.user.js)
Userstyles:	disabled
Other extensions used:	Windows Defender

Issue configuration

Import

[Alex-302]

On my end it works again after disabling routing via AdGuard of arduino-cli.exe (may be located in different places).