blank page in ds-Event Calendar Pro v2.3.5 (Concrete 8.03)

In the addon ds-Event Calendar Pro v2.3.5 all functions work, except for the function "add event". When I want to add an event, a blank page occurs (in Chrome-developer: 500 internal server error). See the attachment (calendar-event-error.jpg) for the print screen of Chrome.
I already contacted the developer IceMan, But he checked it out in his environment 8.03 and 8.1 without faults. So he advised me to contact the forum. According to him maybe it has to do with the Concrete core or it has to do with the PHP-version.
How can I solve this problem?

This is my environment:
# concrete5 Version
Core Version - 8.0.3
Version Installed - 8.0.3
Database Version - 20161216000000
# concrete5 Packages
Event Calendar PRO (2.3.5)
# Server Software
# Server API
# PHP Version
# PHP Extensions
apache2handler, bcmath, bz2, calendar, Core, ctype, curl, date, dom, exif, fileinfo, filter, ftp, gd, gettext, gmp, hash, iconv, imagick, imap, json, libxml, mbstring, mcrypt, mysqli, mysqlnd, openssl, pcre, PDO, pdo_mysql, pdo_sqlite, Phar, posix, pspell, Reflection, session, shmop, SimpleXML, snmp, soap, sockets, SPL, sqlite3, standard, sysvmsg, sysvsem, sysvshm, tidy, tokenizer, wddx, xml, xmlreader, xmlrpc, xmlwriter, Zend OPcache, zip, zlib
# PHP Settings

1 Attachment

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mhawke replied on at Permalink Reply
Try clicking on the second line in the error message. Sometimes the link will provide a reason for the crash. Also, what shows up in your Dashboard->Reports->Logs or in the server logs themselves?
MrKDilkington replied on at Permalink Best Answer Reply
Hi mesign,

This is likely related to an issue that has been fixed in concrete5 8.1. If so, updating should resolve it.

"Embedding CKEditor in single pages triggers fatal error when CSS and JavaScript Cache is enabled #4922"
mesign replied on at Permalink Reply
Problem solved by updating from Concrete5 version 8.03 to 8.1.0