Xcode 9 - Test target X encountered an error (Unable to connect to Test Manager)

Question

I'm trying to run some of my Unit Tests but it kept giving me error:

Showing Recent Issues
Test target X encountered an error (Unable to connect to test manager on d7306c4130298fbc17bc0985ec02f808dcdc1374 If you believe this error represents a bug, please attach the log file at /var/folders/2h/0y4yjs6s7l307mbr6pk1xdl00000gn/T/com.apple.dt.XCTest/IDETestRunSession-CF80FA05-C8ED-4FCE-A04B-4A8070F21059/X-E8F39B10-0CDC-43D5-9BED-CD2D0F6081DA/Session-X-2018-01-08_161733-D3YlRc.log)

I've tried searching for this type of error but to no avail. Anybody got any ideas?

Answer 1

Simply restarting the device fixed this for me (iOS 11.3)

Answer 2

I resolved this issue by doing a hard restart of my device. For my iPhone 8, I followed these instructions from macrumors.com: Hard restart iPhone 8

Alternatively, if you're an libimobiledevice user you can use /usr/local/bin/idevicediagnostics restart from your mac's terminal.

Hope this helps

Answer 3

I restarted my iPhone 6 (iOS 11.2.6) in a normal way to resolve the same issue.