我有一个程序可以转换PDF来创建缩略图。它使用这个转换命令：
convert -thumbnail 400x600 -background white -alpha remove " . escapeshellarg($pathToFile) . "[0]
我遇到的问题如下：
ERROR loggerTechnique - [Script][OK][thumbnails][UP][document not converted ! (QXcbConnection: Could not connect to display)][thumbnails]
INFO loggerTechnique - [Script][OK][thumbnails][UP][Process n°24/63898 (RES_ID => 69276, FORMAT => pdf, PATH => /var/docservers/FASTHD_MAN/2017/10/0001//0929.pdf)][thumbnails]
您是否知道我为何会遇到QXcbConnection: Could not connect to display错误？