I'm looking to test VirtualBox 5.0 release or 5.0.x latest development stable build and get this error:

Effective UID is not root (euid=501 egid=20 uid=501 gid=20) (rc=-10)

The Please try reinstalling VirtualBox. advice doesn't help.

I am guessing this is what happens when software designed to write files to the new protected system area on El Capitan (SIP/System Integrity Protection) is run, but I don't see any Apple Documentation explaining how to interact with apps or disable that new feature.

Mac OS X
ProductVersion: 10.11
BuildVersion:   15A244d

VirtualBox - both production 5.0 and stable test build 5.0.x/5.0.x revision 101955 crash as follows:

Process:               VirtualBox [3459]
Path:                  /Applications/VirtualBox.app/Contents/MacOS/VirtualBox
Identifier:            org.virtualbox.app.VirtualBox
Version:               5.0.1 (5.0.1)
Code Type:             X86-64 (Native)
Parent Process:        ??? [1]
Responsible:           VirtualBox [3459]
User ID:               501

Date/Time:             2015-08-10 09:09:41.134 -0400
OS Version:            Mac OS X 10.11 (15A244d)
Report Version:        11
Anonymous UUID:        EE01F573-7E91-04EB-9C15-BC7F65B04F93

Sleep/Wake UUID:       99D3F30E-0E72-4E05-9E59-8D29819BB8D8

Time Awake Since Boot: 19000 seconds
Time Since Wake:       1100 seconds

Crashed Thread:        0  Dispatch queue: com.apple.main-thread

Exception Type:        EXC_CRASH (SIGABRT)
Exception Codes:       0x0000000000000000, 0x0000000000000000
Exception Note:        EXC_CORPSE_NOTIFY

Application Specific Information:
crashed on child side of fork pre-exec

Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
0   libsystem_kernel.dylib          0x00007fff8a8dc0ae __pthread_kill + 10
1   libsystem_pthread.dylib         0x00007fff89031665 pthread_kill + 90
2   libsystem_c.dylib               0x00007fff943273fb abort + 129
3   QtCoreVBox                      0x000000010dcaddf5 qt_message_output(QtMsgType, char const*) + 117
4   QtCoreVBox                      0x000000010dcadfd7 qt_message_output(QtMsgType, char const*) + 599
5   QtCoreVBox                      0x000000010dcae19a qFatal(char const*, ...) + 170
6   VirtualBox.dylib                0x000000010d323daf TrustedError + 831
7   org.virtualbox.app.VirtualBox   0x000000010d2de643 0x10d2db000 + 13891
8   org.virtualbox.app.VirtualBox   0x000000010d2de6df 0x10d2db000 + 14047
9   org.virtualbox.app.VirtualBox   0x000000010d2ded08 0x10d2db000 + 15624
10  org.virtualbox.app.VirtualBox   0x000000010d2dcfa4 start + 52

1 Answer 1


To resolve this on El Capitan when using Virtualbox versions lower than 6.x run the following from terminal:

for bin in VirtualBox VirtualBoxVM VBoxNetAdpCtl VBoxNetDHCP VBoxNetNAT VBoxHeadless; do
    sudo chmod u+s "/Applications/VirtualBox.app/Contents/MacOS/${bin}"

Source: VirtualBox does not start on Mac OS X - Super User

  • You rock! I just found that answer and was testing before answering. I'll probably self answer some other of the options - but this is the superior and correct answer.
    – bmike
    Aug 10, 2015 at 13:29
  • This might work -- but it is a good idea? Usually setting the setuid bit randomly on binaries that weren't designed to be setuid is not a good idea -- for one thing, it can open up security holes. I would prefer to see some justification of why this answer is safe and reasonable. Unfortunately, the original source provides no such information.
    – D.W.
    Aug 12, 2015 at 2:43
  • @D.W. Well said. Virtual box is probably neither. It pokes holes everywhere you might want to compromise security. Kind of like many AV products.
    – bmike
    Mar 14, 2017 at 10:53
  • Helped me on Manjaro Linux
    – Anwar
    Apr 6, 2019 at 15:37

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