LLDB RPC server freezes app

Question

For the past months I have not been able to debug macOS or iOS apps through Xcode. What happens is the following:

1. Build and run app from Xcode.
2. Xcode says app is running, but no app has appeared and no debug output from app either.
3. Kill the process lldb-rpc-server.
4. App appears and runs as normal, but Xcode is no longer debugging.
5. Start a new debugging session by attaching it to the app's process.
6. App freezes again, until lldb-rpc-server is killed.

This OpenRadar has the same description.

I have tried re-installing Xcode (including command-line tools), but it didn't help. Any ideas?

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Xcode: Version 9.3.1 (9E501)

MacOS: 10.13.4 (17E199)

Answer 1

The cause of this was that I had installed a GDB/LLDB-extension called Voltron. I was unaware that the installation also created/modified the .lldbinit in the home folder. Removing this file fixed the issue. See also this issue for Voltron.

Got some very good help from Apple.