Device freezes and not able to hit breakpoints when disconnecting USB and reattaching it while debugging.

[haavamoa]

Apple platform

iOS

Framework version

net8.0-*

Affected platform version

.NET 8.0.100

Description

I upgraded to Xcode 16 last week, but after reading this post I removed it and installed Xcode 15.4. After doing so, I started noticing that debugging my app with a device sometimes freezes the app and I loose breakpoints.

Setup:

• 2x devices, iOS 17.5.1 and iOS 18.0. Same issue for both.
• Using Intellij Rider and VS Code + Meteor. Same issue for both.
• Debugging using USB.

It seems like this is a known issue from Xcode 16 release notes

I want to create this issue so others can comment on their workarounds if others are experiencing the same behaviour as me.

Steps to Reproduce

1. Connect a iPhone to your Mac.
2. Debug a MAUI app, make sure you can set breakpoints and they are hit.
3. Disconnect the USB
4. Connect the USB
5. Start debugging after it was connected.
6. Notice that breakpoints is not hit and the app randomly freezes for a couple of minutes.

Did you find any workaround?

• It seems like rebooting my device stops the issue, but once I disconnect the USB and reattach it, the bug seem to come back.

• It seems like this is a known issue from Xcode 16 release notes, and the workaround mentioned by Apple seems to work for me.

Relevant log output

No response

[rolfbjarne]

This is interesting, and I don't really have any ideas what might be causing it, except the Xcode issue you linked to.

• Did your colleague who can also reproduce this ever install Xcode 16?

• Can you try adding this to your csproj to see if it makes a difference (this might only work with VS, not VSCode, nor any other IDEs):

  <PropertyGroup>
      <IOSDebuggerConnectOverUsb>false</IOSDebuggerConnectOverUsb>
  	<IOSDebugOverWiFi>true</IOSDebugOverWiFi>
  </PropertyGroup>

[haavamoa]

• Did your colleague who can also reproduce this ever install Xcode 16?

Yes.

• Can you try adding this to your csproj to see if it makes a difference (this might only work with VS, not VSCode, nor any other IDEs):

  <PropertyGroup>
      <IOSDebuggerConnectOverUsb>false</IOSDebuggerConnectOverUsb>
  	<IOSDebugOverWiFi>true</IOSDebugOverWiFi>
  </PropertyGroup>
  

I tried it running Intellij Rider, there is no difference. I don't have VS 4 Mac as it's not supported anymore, and I do not have a Windows machine to test VS 4 Windows.

---

Unfortunately, it now happened again and I tried following my own workarounds, none of them works :(

In this scenario, I lost breakpoints from a USB disconnect. I tried to turn off Wifi on Mac and Airplane mode on device. I disconnected the USB and reattached it. Cleaned my bin folders, and started debugging. No breakpoints is hitting.
I tried rebooting the device, cleaned my bin folders and started debugging. No breakpoints is hit.

there's no particular reason why I clean my bin folders, its just my paranoia kicking in :D

I closed the app, and Intellij Rider still thinks my app is running, with breakpoints disabled:

:( So now I am completely stuck debugging my iOS app.

This is the project I am running, specifically the Components app project.

[rolfbjarne]

Do you see the same behavior if you create a new project?

[haavamoa]

I can try a brand new project, but I see the same behaviour for all of my three app project I work on in my day job. I'll test a new one now.

[haavamoa]

Just created a new project, no breakpoints are hit :(

[haavamoa]

Tried my workaround for the new project when this bug appeared:

I just turned off Wifi + enabled Airplane mode, then redeployed, it now hits my breakpoint.
Once I noticed it hit my breakpoint, I turn on Wifi + disable Airplane mode, then redeployed, it now hits my breakpoint again.

I then headed over to DIPS.Mobile.UI (original project I had issue with), it still has issues and no breakpoint is hit.

This is confusing...

[rolfbjarne]

This is quite puzzling, but here's an idea to try to fully revert to Xcode 15.4, which involves re-installing the packages from Xcode 15.4 that installs stuff into the system (replacing the ones that were installed by Xcode 16.0).

The packages are in /Applications/Xcode.app/Contents/Resources/Packages, and I believe they have to be installed in a certain order to not fail.

Here's a shell script to do it (make sure to update the path to Xcode):

XCODE=/Applications/Xcode_15.4.0.app
PKGS="MobileDevice.pkg MobileDeviceDevelopment.pkg XcodeSystemResources.pkg"
for pkg in $PKGS; do
	echo "Installing $pkg"
	sudo /usr/sbin/installer -dumplog -verbose -pkg "$XCODE/Contents/Resources/Packages/$pkg" -target /
	echo "Installed $pkg"
done

Warning: I believe this to be safe, but it may leave your system in a confused state where things work worse than before.

[haavamoa]

Fortunately, you decided to launch Xcode 16 support with .NET 8, for me this means that I can upgrade to it. Hopefully it will fix things for me :)
I will report back here once I've done so.

[haavamoa]

Alright, good news. This looks like it got resolved.
So I had issues with DIPS.Mobile.UI project yesterday. Today I upgraded to Xcode 16 and the new Workloads. When I started the app, it failed to connect to debugger instantly. I cleaned my bin folders and redeployed. Now it works like it should.
Even disconnecting and reconnecting USB works like before.

I will force this into our pipeline for my colleagues and give feedback here if we notice problems with the new update :)

Have a nice weekend!

[rolfbjarne]

Alright, good news. This looks like it got resolved. So I had issues with DIPS.Mobile.UI project yesterday. Today I upgraded to Xcode 16 and the new Workloads. When I started the app, it failed to connect to debugger instantly. I cleaned my bin folders and redeployed. Now it works like it should. Even disconnecting and reconnecting USB works like before.

I will force this into our pipeline for my colleagues and give feedback here if we notice problems with the new update :)

Have a nice weekend!

That's great news! Hoping it will stay working 🤞

[Vetle444]

@rolfbjarne I still have issues after upgrading to xcode 16 and xamarin.ios 8303. However, it appears it is only reproduced when I am at the office, and not when I am working from home, where I do not have access to our internal network.

It also has nothing to do with disconnecting and reconnecting the usb.

Edit: Looks like I got it working by using the same network on device and mac and then restarting my mac, which I didn't need to before.

[microsoft-github-policy-service]

Hi @haavamoa. Due to inactivity, we will be closing this issue. Please feel free to re-open this issue if the issue persists. For enhanced visibility, if over 7 days have passed, please open a new issue and link this issue there. Thank you.

[haavamoa]

It's still happening for me, but I am unable to understand when it does. It can happen when I switch between VPN and non-VPN, but sometimes it happens when I am on the same network and I have to clear my bin/obj folders for it to connect again... This is very unfortunate

[haavamoa]

I just realised that I had to downgrade iOS workload due to this issue:
dotnet/maui#25139 (comment)

Which might be why I suddenly started getting this issues again.