*** This bug is a duplicate of bug 1296425 *** https://bugs.launchpad.net/bugs/1296425
I found the root cause and wrote it in comments 21 and 22 of the duplicate bug: https://bugs.launchpad.net/ubuntu/+source/ubuntu-drivers- common/+bug/1296425 SUMMARY: ubuntu-drivers-common scripts (sl-modem.py) are calling "aplay -l" with an empty environment, thus "aplay -l" creates a new "pulseaudio" process instead of using the session's pulseaudio, which interferes with sound card recognition (device busy errors). There is a one liner fix in the comment. Kubuntu calls ubuntu-drivers-common scripts on login to KDE, but the issue affects also Ubuntu users if they run any program that calls those scripts, until they restart. Cheers, Juan Manuel Cabo -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1325282 Title: USB microphone inputs not detected by Pulseaudio on Kubuntu Trusty To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/pulseaudio/+bug/1325282/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs