visual studio 2017 failed to update to 15.0.26430.16 and crashed when installer start

[weixin_38049129]

vs2017 notified me to update. but failed to update to 15.0.26430.16 and crashed when installer start.
pls help me to check.
my current version is 15.0.26430.15.
update target is 15.0.26430.16.
my system is windows10 64bit.
the dd_vs_bootstrapper_decompression_log show below error.
[7/21/2017, 10:30:58] === Logging started: 2017/07/21 10:30:58 ===
[7/21/2017, 10:30:58] Executable: C:\ProgramData\Microsoft\VisualStudio\Packages\_bootstrapper\vs_bootstrapper.exe v15.0.26430.16
[7/21/2017, 10:30:58] --- logging level: standard ---
[7/21/2017, 10:30:58] Directory 'C:\Users\cc\AppData\Local\Temp\0275a5d829da34746adcbe\' has been selected for file extraction
[7/21/2017, 10:30:58] Extracting files to: C:\Users\cc\AppData\Local\Temp\0275a5d829da34746adcbe\
[7/21/2017, 10:30:59] Extraction took 312 milliseconds
[7/21/2017, 10:30:59] Executing extracted package: 'vs_bootstrapper_d15\vs_setup_bootstrapper.exe ' with commandline ' --update update --installPath "C:\Program Files (x86)\Microsoft Visual Studio\2017\Community" --activityId 9e56661b-531f-41fb-91e7-95399aadea0c
/finalizeinstall'
[7/21/2017, 10:31:6] The entire Box execution exiting with result code: 0x0
[7/21/2017, 10:31:6] Launched extracted application exiting with result code: 0xc0000005
[7/21/2017, 10:31:6] === Logging stopped: 2017/07/21 10:31:06 ===