running xvfb-run returns missing extension RANDR

Question

When running a program returns an missing extension RANDR

# xvfb-run ./a.out
Xlib:  extension "RANDR" missing on display ":99".

Answer 1

This is simply a warning. If you check the file that xvfb is writing to you'll see that it is actually working. I experienced this issue myself.

Answer 2

Xvfb doesn't support rotating or resizing. Unless your application actually needs to use the Xrandr extension, the warning is harmless:

---

$ xvfb-run -a xdpyinfo | sed '/^$/q'; echo $?
name of display:    :99
version number:    11.0
vendor string:    The X.Org Foundation
vendor release number:    11501000
X.Org version: 1.15.1
maximum request size:  16777212 bytes
motion buffer size:  256
bitmap unit, bit order, padding:    32, LSBFirst, 32
image byte order:    LSBFirst
number of supported pixmap formats:    6
supported pixmap formats:
    depth 1, bits_per_pixel 1, scanline_pad 32
    depth 4, bits_per_pixel 8, scanline_pad 32
    depth 8, bits_per_pixel 8, scanline_pad 32
    depth 16, bits_per_pixel 16, scanline_pad 32
    depth 24, bits_per_pixel 32, scanline_pad 32
    depth 32, bits_per_pixel 32, scanline_pad 32
keycode range:    minimum 8, maximum 255
focus:  PointerRoot
number of extensions:    23
    BIG-REQUESTS
    DAMAGE
    DOUBLE-BUFFER
    DPMS
    DRI3
    GLX
    Generic Event Extension
    MIT-SCREEN-SAVER
    MIT-SHM
    Present
    RECORD
    RENDER
    SECURITY
    SGI-GLX
    SHAPE
    SYNC
    X-Resource
    XC-MISC
    XFIXES
    XInputExtension
    XKEYBOARD
    XTEST
    XVideo
default screen number:    0
number of screens:    1

0

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$ xvfb-run -a xrandr; echo $?
RandR extension missing
1