MessageSendFailure: Message send failure for relaunch

I have a project that runs smoothly and works on the Simulator, but does not render on the Canvas. Neither the Live Preview nor the view on the Canvas works and aborts with the error:

MessageSendFailure: Message send failure for relaunch.

I have attached the error log for you.

I hope you guys can help me out. It sucks to work like this. By the way, it's not because of the swift file. Also with new SwiftUI views the error comes.

What have I tried so far:

  • reinstall xCode
  • Clear build cache
  • Create a new project

Thanks for your help!

previews_diagnostics_summary.txt
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OnlyWaldfee
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Hi,

Sorry to hear you are having problems getting previews working.

Crash logs for the preview app will show up in ~/Library/Logs/DiagnosticReports/. It can sometimes take a few minutes for it to generate, so give it a bit time and then see if any are there. Hopefully that will give you some helpful hints on what is causing the crash.

To start from a fresh slate you can use the terminal app and run xcrun simctl --set previews delete all.

If that still doesn't resolve issue then probably best next step will be to file a feedback with diagnostics. We will need the diagnostics Xcode Previews generates in order to make sure we understand the error the previews system is encountering.

If you are having issues with macOS, catalyst or on-device iOS previews then download and install the logging profile for your device. Instructions and profiles are available here: https://developer.apple.com/bug-reporting/profiles-and-logs/?name=swift Attach the sysdiagnose to the radar as well as the diagnostics using the instructions below.

Then when you get an error in Xcode Previews, an error banner appears in the canvas

  1. Click the "Diagnostics" button in that banner
  2. In the sheet that appears, click "Generate Report" in the bottom left of the sheet
  3. Attach (or make from the folder) the resulting zip file to the bug (will be named something like previews-diagnostics-0123456789.zip)
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Frameworks Engineer
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I have submitted a bug report. Maybe there is a developer who has already found a solution.

Don't know what "Attach the sysdiagnose to the radar" means. Can you explain this a bit more?

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OnlyWaldfee
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  • that means attach the sysdiagnose to the feedback/bug report you filed. More instructions on how to generate one at the URL mentioned above

    —
    Frameworks Engineer
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