Can't share calenders with groups anymore - Owncloud 10.1.0

[FKBOX]

calender app is 1.6.1

1. go on calender app an share with group, find the group but nothing happens.
2. public share works in browser
3. deakativated, aktivated, deinstalled, installed same as before

Server configuration

Operating system: ubuntu 16.04 LTS

Web server: apache2

Database: mysql

PHP version: 7.0

ownCloud version: (10.1.0)

Calendar version: (1.6.2)

Updated from an older installed version or fresh install:
Started with updates (repository) from 9.1 my first version.

List of activated apps:
Enabled:

• activity: 2.4.2
• audioplayer: 2.6.0
• calendar: 1.6.2
• comments: 0.3.0
• configreport: 0.1.1
• contacts: 1.5.5
• dav: 0.4.0
• federatedfilesharing: 0.3.1
• federation: 0.1.0
• files: 1.5.1
• files_external: 0.7.1
• files_pdfviewer: 0.10.0
• files_sharing: 0.11.0
• files_texteditor: 2.3.0
• files_trashbin: 0.9.1
• files_versions: 1.3.0
• files_videoplayer: 0.9.8
• firstrunwizard: 1.1
• gallery: 16.1.1
• market: 0.3.0
• notifications: 0.4.1
• onlyoffice: 2.1.3
• ownbackup: 19.1.0
• provisioning_api: 0.5.0
• systemtags: 0.3.0
• templateeditor: 0.4.0
• updatenotification: 0.2.1
  Disabled:
• encryption
• external
• user_external

ownCloud configuration:
"system": {
"updatechecker": false,
"instanceid": "oc8p4nu9wuyk",
"passwordsalt": "REMOVED SENSITIVE VALUE",
"secret": "REMOVED SENSITIVE VALUE",
"trusted_domains": [
"localhost",
"fkbox.de",
"192.168.178.2"
],
"datadirectory": "/var/www/owncloud/data",
"overwrite.cli.url": "https://localhost/owncloud",
"dbtype": "mysql",
"version": "10.1.0.4",
"dbname": "owncloud",
"dbhost": "localhost",
"dbtableprefix": "oc_",
"dbuser": "REMOVED SENSITIVE VALUE",
"dbpassword": "REMOVED SENSITIVE VALUE",
"logtimezone": "UTC",
"installed": true,
"maintenance": false,
"theme": "",
"loglevel": 2,
"mail_from_address": "REMOVED SENSITIVE VALUE",
"mail_smtpmode": "smtp",
"mail_domain": "REMOVED SENSITIVE VALUE",
"mail_smtpsecure": "ssl",
"mail_smtpauthtype": "LOGIN",
"mail_smtphost": "REMOVED SENSITIVE VALUE",
"mail_smtpport": "465",
"mail_smtpauth": 1,
"mail_smtpname": "REMOVED SENSITIVE VALUE",
"mail_smtppassword": "REMOVED SENSITIVE VALUE"
},
"apps": {
"activity": {
"enabled": "yes",
"installed_version": "2.4.2",
"signed": "true",
"types": "filesystem"
},
"audioplayer": {
"enabled": "yes",
"installed_version": "2.6.0",
"signed": "true",
"types": "filesystem"
},
"backgroundjob": {
"lastjob": "5"
},
"bookmarks": {
"enabled": "no",
"installed_version": "0.9.0",
"ocsid": "168710",
"types": ""
},
"calendar": {
"enabled": "yes",
"installed_version": "1.6.2",
"signed": "true",
"types": ""
},
"comments": {
"enabled": "yes",
"installed_version": "0.3.0",
"types": "logging"
},
"configreport": {
"enabled": "yes",
"installed_version": "0.1.1",
"types": "filesystem"
},
"contacts": {
"enabled": "yes",
"installed_version": "1.5.5",
"signed": "true",
"types": ""
},
"core": {
"backgroundjobs_mode": "ajax",
"enable_external_storage": "yes",
"installedat": "1485904804.2576",
"lastcron": "1551538906",
"lastupdateResult": "[]",
"lastupdatedat": "1551538905",
"oc.integritycheck.checker": "[]",
"public_documents": "documents/public.php",
"public_files": "files_sharing/public.php",
"public_webdav": "dav/appinfo/v1/publicwebdav.php",
"shareapi_allow_group_sharing": "yes",
"shareapi_allow_mail_notification": "yes",
"shareapi_allow_public_notification": "yes",
"shareapi_allow_resharing": "no",
"shareapi_allow_social_share": "no",
"shareapi_enabled": "yes",
"shareapi_enforce_links_password_read_only": "no",
"shareapi_enforce_links_password_read_write": "no",
"shareapi_enforce_links_password_write_only": "no",
"vendor": "owncloud"
},
"dav": {
"enabled": "yes",
"installed_version": "0.4.0",
"types": "filesystem"
},
"documents": {
"converter": "local",
"enabled": "no",
"installed_version": "0.13.1",
"ocsid": "168711",
"types": ""
},
"federatedfilesharing": {
"enabled": "yes",
"installed_version": "0.3.1",
"types": "filesystem"
},
"federation": {
"enabled": "yes",
"installed_version": "0.1.0",
"types": "authentication"
},
"files": {
"cronjob_scan_files": "500",
"enabled": "yes",
"installed_version": "1.5.1",
"types": "filesystem"
},
"files_antivirus": {
"av_cmd_options": "",
"av_host": "",
"av_infected_action": "only_log",
"av_max_file_size": "-1",
"av_mode": "executable",
"av_path": "/usr/bin/clamscan",
"av_port": "0",
"av_socket": "/var/run/clamav/clamd.ctl",
"av_stream_max_length": "26214400",
"enabled": "no",
"installed_version": "0.14.0",
"signed": "true",
"types": "filesystem,dav"
},
"files_external": {
"allow_user_mounting": "yes",
"enabled": "yes",
"installed_version": "0.7.1",
"ocsid": "166048",
"types": "filesystem",
"user_mounting_backends": "dav,owncloud,sftp,dropbox,\OC\Files\Storage\SFTP_Key"
},
"files_pdfviewer": {
"enabled": "yes",
"installed_version": "0.10.0",
"ocsid": "166049",
"signed": "true",
"types": ""
},
"files_sharing": {
"enabled": "yes",
"installed_version": "0.11.0",
"types": "filesystem"
},
"files_texteditor": {
"enabled": "yes",
"installed_version": "2.3.0",
"signed": "true",
"types": ""
},
"files_trashbin": {
"enabled": "yes",
"installed_version": "0.9.1",
"types": "filesystem"
},
"files_versions": {
"enabled": "yes",
"installed_version": "1.3.0",
"types": "filesystem"
},
"files_videoplayer": {
"enabled": "yes",
"installed_version": "0.9.8",
"types": ""
},
"firstrunwizard": {
"enabled": "yes",
"installed_version": "1.1",
"ocsid": "166055",
"types": ""
},
"gallery": {
"enabled": "yes",
"installed_version": "16.1.1",
"signed": "true",
"types": ""
},
"market": {
"activity": "2.4.1",
"audioplayer": "2.5.1",
"calendar": "1.6.2",
"contacts": "1.5.5",
"enabled": "yes",
"files_antivirus": "0.14.0",
"files_pdfviewer": "0.10.0",
"files_texteditor": "2.3.0",
"gallery": "16.1.1",
"installed_version": "0.3.0",
"market": "0.3.0",
"onlyoffice": "2.1.3",
"richdocuments": "2.0.4",
"signed": "true",
"templateeditor": "0.4.0",
"types": ""
},
"notifications": {
"enabled": "yes",
"installed_version": "0.4.1",
"types": "logging"
},
"onlyoffice": {
"DocumentServerInternalUrl": "",
"DocumentServerUrl": "http://localhost/owncloud/apps/onlyoffice/",
"StorageUrl": "",
"defFormats": "{"docx":"true","xlsx":"true","pptx":"true","ppsx":"true","txt":"false","csv":"false"}",
"enabled": "yes",
"installed_version": "2.1.3",
"jwt_secret": "",
"ocsid": "174798",
"sameTab": "false",
"settings_error": "Mixed Active Content\u00a0ist nicht m\u00f6glich. HTTPS-Adresse f\u00fcr Document Server ist erforderlich.",
"signed": "true",
"skey": "1523712091541",
"types": "filesystem"
},
"ownbackup": {
"enabled": "yes",
"installed_version": "19.1.0",
"ocsid": "170674",
"signed": "true",
"types": ""
},
"ownnote": {
"enabled": "no",
"installed_version": "1.08",
"ocsid": "168512",
"types": ""
},
"provisioning_api": {
"enabled": "yes",
"installed_version": "0.5.0",
"types": "prevent_group_restriction"
},
"richdocuments": {
"enabled": "no",
"installed_version": "2.0.5",
"ocsid": "174727",
"signed": "true",
"types": "prevent_group_restriction"
},
"systemtags": {
"enabled": "yes",
"installed_version": "0.3.0",
"types": "logging"
},
"tasks": {
"enabled": "no",
"installed_version": "0.9.4",
"ocsid": "164356",
"signed": "true",
"types": ""
},
"templateeditor": {
"enabled": "yes",
"installed_version": "0.4.0",
"signed": "true",
"types": ""
},
"updatenotification": {
"core": "10.0.10",
"enabled": "yes",
"installed_version": "0.2.1",
"ownbackup": "17.3.0",
"types": ""
}
}
}

Are you using external storage, if yes which one: local smb

Are you using encryption: no

Client configuration

Browser: Firefox, edge is the same

Operating system: win10, win 7, ubuntu 16.04

CalDAV-clients: iphone8

[DeepDiver1975]

1. go on calender app an share with group, find the group but nothing happens.

errors in browser or on the server?

[FKBOX]

{"reqId":"#####sxhR1","level":3,"time":"2019-02-21T17:35:22+00:00","remoteAddr":"88.94.##.##","user":"Frank_K","app":"OCP\Share","method":"GET","url":"/owncloud/ocs/v1.php/apps/files_sharing/api/v1/sharees?format=json&search=chr&perPage=200&itemType=principals","message":"Sharing backend for principals not found"}
Thats the message of owncloud.log how can I fix that?

[MBeule]

I have the same problem!

[FKBOX]

It seems that owncloud ist file-cloud an no more an no help. The only thing to solve the problem ist to change to nextcloud. I do 'next' when I have time!

[Julian1998]

@FKBOX This calendar app is written by the community... Not the ownCloud team - We are just helping as much as we can! It's the same for Nextcloud.

[FKBOX]

Calender and contacts is close important as file-cloud for me. Is nobody here who know how to fix missing backend?

[alfredbuehler]

I see the same "Sharing backend for principals not found" messages on my system, but sharing works as expected. Problem must be somewhere else.

[FKBOX]

SELECT * FROM oc_dav_shares => no results, no data set
Columns: id, principaluri, publicuri, type, access, resourceid
SELECT * FROM oc_calendarsubscriptions => no results, no data set
Columns: id, uri, principaluri, source, displayname, refreshrate, calendarorder, calendarcolor, striptodos, stripalarms, stripattachments, lastmodified

what is wrong with tables?

[alfredbuehler]

Table oc_dav_shares is empty, because you cannot/don't have shares.

[FKBOX]

I had shares before! Who deleted them? Or which update deleted, crashed shares???

[alfredbuehler]

IIRC you wrote on central, that you updated the os from the repos. My best guess is, that something went terribly wrong. For unknown reasons, ownCloud failed in migrating you existing db contents. Unfortunately I don't see any straight way out.

[FKBOX]

Any help in meantime? I can share a calenders with public link, but not to group or user?!

[alfredbuehler]

Not really. I still think that your system blocks something. I hope yo had a look at the browser logs as well, as suggested above.