The subject says it all. When uploading certificate, this error appears:
This page has expired
The request cannot be completed
because this page has expired
/var/log/messages says:
May 17 14:41:09 dpi httpd: [ERROR] Nethgui\Framework: CSRF token verification failed!
/var/log/httpd-admin/access_log contains:
10.1.8.252 - - [17/May/2018:14:25:18 +0200] "GET /en-US/Pki HTTP/1.1" 200 19734
10.1.8.252 - - [17/May/2018:14:40:39 +0200] "GET /en-US/Pki/Upload.json?_=1526559919524 HTTP/1.1" 200 429
10.1.8.252 - - [17/May/2018:14:40:39 +0200] "GET /css/img/mandatory_normal.png HTTP/1.1" 200 250
10.1.8.252 - - [17/May/2018:14:40:39 +0200] "GET /css/img/red-inset-normal.png HTTP/1.1" 200 217
10.1.8.252 - - [17/May/2018:14:40:49 +0200] "POST /en-US/Pki/Upload.json HTTP/1.1" 400 59
10.1.8.252 - - [17/May/2018:14:41:51 +0200] "GET /en-US/Pki HTTP/1.1" 200 19734
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /css/ui/jquery-ui-1.8.16.custom.css HTTP/1.1" 200 33719
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /css/base.css HTTP/1.1" 200 17784
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /css/font-awesome.css HTTP/1.1" 200 33233
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/jquery-migrate-1.4.1.min.js HTTP/1.1" 200 10056
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /css/jquery.timepicker.css HTTP/1.1" 200 1584
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/jquery.timepicker.min.js HTTP/1.1" 200 15297
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/percent.js HTTP/1.1" 200 910
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/jquery.dataTables.min.js HTTP/1.1" 200 82638
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/jquery-1.12.4.min.js HTTP/1.1" 200 97163
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/file-size.js HTTP/1.1" 200 1213
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/ip-address.js HTTP/1.1" 200 1921
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/mustache.js HTTP/1.1" 200 16469
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /en-US/Resource/27dd3ddb.css HTTP/1.1" 200 226
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /en-US/Resource/753b61bd.js HTTP/1.1" 200 57374
10.1.8.252 - - [17/May/2018:14:41:52 +0200] "GET /js/jquery-ui-1.8.23.min.js HTTP/1.1" 200 200748
10.1.8.252 - - [17/May/2018:14:41:53 +0200] "GET /js/datatable-en-US.json HTTP/1.1" 200 726
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /images/logo.png HTTP/1.1" 200 4031
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /css/ui/images/ui-bg_inset-soft_75_e6e6e6_1x100.png HTTP/1.1" 200 95
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /css/ui/images/ui-bg_flat_75_cccccc_40x100.png HTTP/1.1" 200 180
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /css/ui/images/ui-icons_888888_256x240.png HTTP/1.1" 200 4369
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /css/img/red-inset-normal.png HTTP/1.1" 200 217
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /css/img/mandatory_normal.png HTTP/1.1" 200 250
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /fonts/fontawesome-webfont.woff2?v=4.5.0 HTTP/1.1" 200 66624
10.1.8.252 - - [17/May/2018:14:41:54 +0200] "GET /images/light-polygons/toolbar.png HTTP/1.1" 200 108933
Any help is welcomed.