PgAmin can not start when the PYTHONPATH is added on win10

I installed PostgreSQL 10 on win10 system.
In order to use QGIS with python, I add the PYTHONPATTH into environment
variable，as below：

C:\Program Files\QGIS 2.18\bin;C:\Program Files\QGIS
2.18\apps\Python27\lib;C:\Program Files\QGIS 2.18\apps\qgis\bin;C:\Program
Files\QGIS 2.18\apps\qgis\python;C:\Program Files\QGIS
2.18\apps\qgis\python\qgis;C:\Program Files\QGIS
2.18\apps\Python27\Lib\site-packages;C:\Program Files\QGIS
2.18\apps\Python27\DLLs;

After PYTHONPATH added, PgAdmin can not start with message "The application
server could not be contacted" . When I delete the PYTHONPATH, PdAdmin start
nomarlly.

Any solution for this problem if I don't want to delete PYTHONPATH from
environment variable.

Thanks

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