I have an Apple mini displayport to VGA adapter connected to an older Samsung SyncMaster 906BW. First time I plugged it in everything was working just fine extending my desktop as expected. Yosemite detected it as a SyncMaster monitor. The external monitor would wake up when my macbook air came out of a short sleep.
I had to leave for a couple hours came back and woke it out of a deeper/longer sleep, the macbook air struggled to wake up and the built in monitor stayed very dark (but could see the login screen) for a second then it lit up normally but the external monitor never woke back up. Now whenever I try unplugging/plugging in the displayport dongle into the macbook air and the built in screen will do nothing or it will flicker but no external monitor is detected. I've tried powering down the external monitor, resetting the VGA connectors, verified the monitor works on another computer, tried resetting NVRAM and the SCM on the macbook air.
I'm getting the following errors in my console log every time I plug in the displayport to VGA dongle now (regardless if the external monitor is connected to it). I can't tell if the dongle is fried or if it's my macbook air? Does anyone else have this problem?
1/29/15 11:40:19.111 PM WindowServer[94]: Received display connect changed for display 0x4273c00
1/29/15 11:40:19.113 PM WindowServer[94]: Found 16 modes for display 0x04273c00 [16, 0]
1/29/15 11:40:19.139 PM WindowServer[94]: Received display connect changed for display 0x3f003d
1/29/15 11:40:19.139 PM WindowServer[94]: Found 1 modes for display 0x003f003d [1, 0]
1/29/15 11:40:19.139 PM WindowServer[94]: Received display connect changed for display 0x3f003e
1/29/15 11:40:19.139 PM WindowServer[94]: Found 1 modes for display 0x003f003e [1, 0]
1/29/15 11:40:19.151 PM WindowServer[94]: Display 0x04273c00: GL mask 0x1; bounds (0, 0)[1440 x 900], 16 modes available
Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9cf0, S/N 0, Unit 0, Rotation 0
UUID 0x933c106c08bc09aaf750c2a74a119def, ColorSpace { 1918466841 }
1/29/15 11:40:19.151 PM WindowServer[94]: GLCompositor: GL renderer id 0x01024500, GL mask 0x0000000f, accelerator 0x00003aa3, unit 0, caps QEX|MIPMAP, vram 1536 MB
texture max 16384, viewport max {16384, 16384}, extensions NPOT|GLSL|FLOAT
1/29/15 11:40:19.151 PM WindowServer[94]: Display 0x003f003f: GL mask 0x8; bounds (2464, 0)[1 x 1], 2 modes available
off-line, enabled, OpenGL-accel, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 3, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff
1/29/15 11:40:19.152 PM WindowServer[94]: GLCompositor: GL renderer id 0x01024500, GL mask 0x0000000f, accelerator 0x00003aa3, unit 0, caps QEX|MIPMAP, vram 1536 MB
texture max 16384, viewport max {16384, 16384}, extensions NPOT|GLSL|FLOAT
1/29/15 11:40:19.152 PM WindowServer[94]: Display 0x003f003e: GL mask 0x4; bounds (2465, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 2, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff
1/29/15 11:40:19.152 PM WindowServer[94]: Display 0x003f003d: GL mask 0x2; bounds (2466, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff
1/29/15 11:40:19.161 PM WindowServer[94]: Display 0x04273c00: Unit 0: Startup Mode 1440 x 900, CGSThirtytwoBitColor, Resolution 1, ioModeID 0x80001000, ioModeDepth 0x0, IOReturn 0x0
1/29/15 11:40:19.161 PM WindowServer[94]: CGXDisplaysDidReconfigure: Display added
1/29/15 11:40:19.162 PM WindowServer[94]: CGXDisplaysDidReconfigure: Display removed
1/29/15 11:40:19.164 PM WindowServer[94]: Display 0x04273c00: GL mask 0x1; bounds (0, 0)[1440 x 900], 16 modes available
Main, Active, on-line, enabled, built-in, boot, OpenGL-accel, Vendor 610, Model 9cf0, S/N 0, Unit 0, Rotation 0
UUID 0x933c106c08bc09aaf750c2a74a119def, ColorSpace { 1918466841 }
1/29/15 11:40:19.164 PM WindowServer[94]: GLCompositor: GL renderer id 0x01024500, GL mask 0x0000000f, accelerator 0x00003aa3, unit 0, caps QEX|MIPMAP, vram 1536 MB
texture max 16384, viewport max {16384, 16384}, extensions NPOT|GLSL|FLOAT
1/29/15 11:40:19.164 PM WindowServer[94]: Display 0x003f003f: GL mask 0x8; bounds (2464, 0)[1 x 1], 2 modes available
off-line, enabled, OpenGL-accel, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 3, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff
1/29/15 11:40:19.164 PM WindowServer[94]: GLCompositor: GL renderer id 0x01024500, GL mask 0x0000000f, accelerator 0x00003aa3, unit 0, caps QEX|MIPMAP, vram 1536 MB
texture max 16384, viewport max {16384, 16384}, extensions NPOT|GLSL|FLOAT
1/29/15 11:40:19.164 PM WindowServer[94]: Display 0x003f003e: GL mask 0x4; bounds (2465, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 2, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff
1/29/15 11:40:19.165 PM WindowServer[94]: Display 0x003f003d: GL mask 0x2; bounds (2466, 0)[1 x 1], 1 modes available
off-line, enabled, Vendor ffffffff, Model ffffffff, S/N ffffffff, Unit 1, Rotation 0
UUID 0xffffffffffffffffffffffffffffffff
1/29/15 11:40:19.188 PM WindowServer[94]: MPAccessSurfaceForDisplayDevice: Set up page flip mode on display 0x04273c00 device: 0x7fbef2511fe0 isBackBuffered: 1 numComp: 3 numDisp: 3
1/29/15 11:40:21.139 PM WindowServer[94]: **DMPROXY** (2) Found `/System/Library/CoreServices/DMProxy'. Run with arg = -discovery
1/29/15 11:40:21.162 PM WindowServer[94]: **DMPROXY** (2) Found `/System/Library/CoreServices/DMProxy'. Run with arg = -discovery
1/29/15 11:40:21.186 PM WindowServer[94]: CGXSetDisplayColorProfileAndTransfer: Display 0x04273c00: Unit 0; ColorProfile { 1918466841 }; TransferTable (256, 12)
1/29/15 11:40:21.189 PM com.apple.AmbientDisplayAgent[154]: AMBD Agent: xpc connection became invalid during event handler
1/29/15 11:40:21.228 PM WindowServer[94]: CGXSetDisplayColorProfileAndTransfer: Display 0x04273c00: Unit 0; ColorProfile { 1918466841 }; TransferTable (256, 12)
1/29/15 11:40:21.231 PM com.apple.AmbientDisplayAgent[154]: AMBD Agent: xpc connection became invalid during event handler
1/29/15 11:40:21.243 PM DMProxy[664]: AMBD Services: connection interrupted: com.apple.AmbientDisplayAgent (Connection interrupted)
1/29/15 11:40:21.253 PM com.apple.AmbientDisplayAgent[154]: AmbientDisplayAgent started
1/29/15 11:40:21.253 PM WindowServer[94]: CGXSetDisplayColorProfileAndTransfer: Display 0x04273c00: Unit 0; ColorProfile { 1918466841 }; TransferTable (256, 12)
1/29/15 11:40:21.259 PM com.apple.AmbientDisplayAgent[154]: AMBD initializing devices
1/29/15 11:40:21.283 PM com.apple.AmbientDisplayAgent[154]: AMBD Agent: xpc connection became invalid during event handler
1/29/15 11:40:21.284 PM DMProxy[665]: AMBD Services: connection interrupted: com.apple.AmbientDisplayAgent (Connection interrupted)
1/29/15 11:40:21.291 PM WindowServer[94]: CGXSetDisplayColorProfileAndTransfer: Display 0x04273c00: Unit 0; ColorProfile { 1918466841 }; TransferTable (256, 12)
1/29/15 11:40:21.295 PM com.apple.AmbientDisplayAgent[154]: AmbientDisplayAgent started
1/29/15 11:40:21.316 PM com.apple.AmbientDisplayAgent[154]: AMBD initializing devices
1/29/15 11:40:21.327 PM com.apple.AmbientDisplayAgent[154]: AMBD Agent: xpc connection became invalid during event handler
Best Answer
The WindowServer is just trying to identify the correct profile for the external monitor.
In some case if it continues (almost endlessly) to do so indicates bad cable/adapter connection.
But it should not be doing that without monitor connected, so replace the displayport to VGA adapter, or test it on another equipment