After last upgrade of Neon developers unstable the KOrganizer crashes. The window appears for some fraction of a second and closes. Running in Konsole gives such output:

vishap@vishap-desktop:~$ korganizer
log_kidentitymanagement: IdentityManager: There was no default identity. Marking first one as default.
""
()
connectToServer "/tmp/akonadi-vishap.YMjd36/akonadiserver.socket"
"/subscriber/korganizer_6163_lHsgWM"
connectToServer "/tmp/akonadi-vishap.YMjd36/akonadiserver.socket"
"ETMCalendar"
connectToServer "/tmp/akonadi-vishap.YMjd36/akonadiserver.socket"
"/subscriber/korganizer_6163_2sRplz"
connectToServer "/tmp/akonadi-vishap.YMjd36/akonadiserver.socket"
log_kidentitymanagement: IdentityManager: There was no default identity. Marking first one as default.
log_kidentitymanagement: IdentityManager: There was no default identity. Marking first one as default.
log_kidentitymanagement: IdentityManager: There was no default identity. Marking first one as default.
log_kidentitymanagement: IdentityManager: There was no default identity. Marking first one as default.
"/subscriber/korganizer_6163_ZYwZKx"
connectToServer "/tmp/akonadi-vishap.YMjd36/akonadiserver.socket"
"/subscriber/korganizer_6163_5fF3VQ"
connectToServer "/tmp/akonadi-vishap.YMjd36/akonadiserver.socket"
"/subscriber/korganizer_6163_ZkgHMd"
connectToServer "/tmp/akonadi-vishap.YMjd36/akonadiserver.socket"
KServiceTypeTrader: serviceType "KOrganizer/Part" not found
done
Connected to "Akonadi" , using protocol version 52
Server says: "Not Really IMAP server"
Connected to "Akonadi" , using protocol version 52
Server says: "Not Really IMAP server"
Connected to "Akonadi" , using protocol version 52
Server says: "Not Really IMAP server"
Connected to "Akonadi" , using protocol version 52
Server says: "Not Really IMAP server"
org.kde.akonadi.ETM: GEN true false true
org.kde.akonadi.ETM: collection: QVector()
Connected to "Akonadi" , using protocol version 52
Server says: "Not Really IMAP server"
Connected to "Akonadi" , using protocol version 52
Server says: "Not Really IMAP server"
Connected to "Akonadi" , using protocol version 52
Server says: "Not Really IMAP server"
org.kde.akonadi.ETM: Subtree: 1 QSet(12, 1, 11)
org.kde.akonadi.ETM: collection: "DeclinedInvitations"
org.kde.akonadi.ETM: collection: "Search"
org.kde.akonadi.ETM: collection: "OpenInvitations"
org.kde.akonadi.ETM: Subtree: 7 QSet(7)
org.kde.akonadi.ETM: collection: "akonadi_ical_resource_0"
org.kde.akonadi.ETM: Subtree: 10 QSet(10)
org.kde.akonadi.ETM: collection: "Дни рождения и годовщины"
org.kde.akonadi.ETM: Fetch job took 301 msec
org.kde.akonadi.ETM: was collection fetch job: collections: 5
org.kde.akonadi.ETM: first fetched collection: "Search"
org.kde.akonadi.ETM: Fetch job took 73 msec
org.kde.akonadi.ETM: was item fetch job: items: 0
org.kde.akonadi.ETM: Fetch job took 97 msec
org.kde.akonadi.ETM: was item fetch job: items: 0
org.kde.akonadi.ETM: Fetch job took 112 msec
org.kde.akonadi.ETM: was item fetch job: items: 0
PLUGIN : identifier "application/octet-stream@QByteArray"
registering Desktop file "/usr/share/akonadi/plugins/serializer//akonadi_serializer_addressee.desktop" for ("text/vcard", "text/directory") @ ("legacy", "default", "KContacts::Addressee")
registering Desktop file "/usr/share/akonadi/plugins/serializer//akonadi_serializer_contactgroup.desktop" for ("application/x-vnd.kde.contactgroup") @ ("legacy", "default", "KContacts::ContactGroup")
registering Desktop file "/usr/share/akonadi/plugins/serializer//akonadi_serializer_kalarm.desktop" for ("application/x-vnd.kde.alarm", "application/x-vnd.kde.alarm.active", "application/x-vnd.kde.alarm.archived", "application/x-vnd.kde.alarm.template") @ ("default", "KAlarmCal::KAEvent")
registering Desktop file "/usr/share/akonadi/plugins/serializer//akonadi_serializer_kcalcore.desktop" for ("text/calendar", "application/x-vnd.akonadi.note", "application/x-vnd.kde.notes") @ ("default", "KCalCore::Incidence*")
registering Desktop file "/usr/share/akonadi/plugins/serializer//akonadi_serializer_mail.desktop" for ("message/rfc822", "message/news", "text/x-vnd.akonadi.note") @ ("legacy", "default", "KMime::Message*")
registering Desktop file "/usr/share/akonadi/plugins/serializer//akonadi_serializer_socialfeeditem.desktop" for ("text/x-vnd.akonadi.socialfeeditem") @ ("Akonadi::SocialFeedItem")
ItemSerializerPluginLoader: found 33 plugins.

PLUGIN : identifier "text/directory@KContacts::Addressee"
PLUGIN : identifier "application/x-vnd.kde.alarm.active@default"
PLUGIN : identifier "application/x-vnd.akonadi.note@KCalCore::Incidence*"
PLUGIN : identifier "text/vcard@default"
PLUGIN : identifier "text/calendar@default"
PLUGIN : identifier "text/calendar@KCalCore::Incidence*"
PLUGIN : identifier "application/x-vnd.kde.alarm@default"
PLUGIN : identifier "application/x-vnd.akonadi.note@default"
PLUGIN : identifier "application/x-vnd.kde.notes@KCalCore::Incidence*"
PLUGIN : identifier "application/x-vnd.kde.notes@default"
PLUGIN : identifier "application/x-vnd.kde.alarm@KAlarmCal::KAEvent"
PLUGIN : identifier "application/x-vnd.kde.alarm.template@KAlarmCal::KAEvent"
PLUGIN : identifier "message/news@KMime::Message*"
PLUGIN : identifier "text/vcard@legacy"
PLUGIN : identifier "application/x-vnd.kde.contactgroup@default"
PLUGIN : identifier "message/rfc822@legacy"
PLUGIN : identifier "message/news@default"
PLUGIN : identifier "text/x-vnd.akonadi.socialfeeditem@Akonadi::SocialFeedItem"
PLUGIN : identifier "application/x-vnd.kde.alarm.archived@KAlarmCal::KAEvent"
PLUGIN : identifier "application/x-vnd.kde.alarm.archived@default"
PLUGIN : identifier "text/vcard@KContacts::Addressee"
PLUGIN : identifier "message/rfc822@KMime::Message*"
PLUGIN : identifier "text/x-vnd.akonadi.note@legacy"
PLUGIN : identifier "application/x-vnd.kde.contactgroup@legacy"
PLUGIN : identifier "text/x-vnd.akonadi.note@KMime::Message*"
PLUGIN : identifier "message/news@legacy"
PLUGIN : identifier "text/directory@legacy"
PLUGIN : identifier "text/directory@default"
PLUGIN : identifier "application/x-vnd.kde.alarm.template@default"
PLUGIN : identifier "application/x-vnd.kde.contactgroup@KContacts::ContactGroup"
PLUGIN : identifier "message/rfc822@default"
PLUGIN : identifier "text/x-vnd.akonadi.note@default"
PLUGIN : identifier "application/x-vnd.kde.alarm.active@KAlarmCal::KAEvent"
korganizer: symbol lookup error: /usr/lib/x86_64-linux-gnu/qt5/plugins/akonadi_serializer_kcalcore.so: undefined symbol: _ZN8KCalCore10ICalFormat13readIncidenceERK10QByteArrayPNS_13ICalTimeZonesE

Please use https://bugs.kde.org/enter_bug.cgi?prod ... mat=guided to report bugs. Thanks.

OK, https://bugs.kde.org/show_bug.cgi?id=366252

I notices that yesterday in both neon developer stable and unstable. Until it is fixed you just need to downgrade the package libkf5calendarcore5 to version 4:15.12.3-0ubuntu1 or whatever is the default version that comes with ubuntu.

Works for me:

jsalatas wrote:I notices that yesterday in both neon developer stable and unstable. Until it is fixed you just need to downgrade the package libkf5calendarcore5 to version
4:15.12.3-0ubuntu1 or whatever is the default version that comes with ubuntu.

Thank you!