Tasks missing when HTTP2 enabled

[kain]

Steps to reproduce

1. Open tasks in browser
2. Start creating task lists with tasks
3. Create 300 or more total tasks

Expected behaviour

All 300 tasks should load

Actual behaviour

Random number of tasks is loading. Every page refresh load different number of tasks. Some task lists missing completely. Some task lists missing some tasks in it.

Server configuration

Operating system: Linux 4.15.0-76-generic #86~16.04.1-Ubuntu SMP Mon Jan 20 11:02:50 UTC 2020 x86_64

Web server: Apache/2.4.7 (apache2handler)

Database: mysql 5.6.39

PHP version: 7.2.15
Modules loaded: Core, date, libxml, openssl, pcre, zlib, bcmath, bz2, calendar, ctype, dba, dom, hash, fileinfo, filter, ftp, gettext, SPL, iconv, json, mbstring, session, standard, posix, Reflection, Phar, shmop, SimpleXML, soap, sockets, exif, sysvmsg, sysvsem, sysvshm, tokenizer, wddx, xml, xmlreader, xmlwriter, zip, mysqlnd, apache2handler, curl, enchant, gd, gmp, imap, interbase, intl, imagick, ldap, mcrypt, mailparse, memcached, mysqli, odbc, PDO, PDO_Firebird, pdo_mysql, PDO_ODBC, pdo_pgsql, pdo_dblib, pdo_sqlite, pgsql, pspell, recode, redis, snmp, ssh2, sqlite3, tidy, xmlrpc, xsl, phalcon, yaml, geoip, raphf, propro, memcache, ionCube Loader, Zend OPcache

Nextcloud version: 18.0.4 - 18.0.4.2

Tasks version: tasks: 0.12.2

Updated from an older Nextcloud or fresh install: Update from 16 to 17 to 18

Signing status:

No errors have been found.

List of activated apps:

Enabled:
  - accessibility: 1.4.0
  - activity: 2.11.0
  - calendar: 2.0.3
  - cloud_federation_api: 1.1.0
  - comments: 1.8.0
  - contacts: 3.3.0
  - dav: 1.14.0
  - deck: 0.8.2
  - federatedfilesharing: 1.8.0
  - federation: 1.8.0
  - files: 1.13.1
  - files_pdfviewer: 1.7.0
  - files_rightclick: 0.15.2
  - files_sharing: 1.10.1
  - files_trashbin: 1.8.0
  - files_versions: 1.11.0
  - files_videoplayer: 1.7.0
  - firstrunwizard: 2.7.0
  - groupfolders: 6.0.6
  - issuetemplate: 0.6.0
  - logreader: 2.3.0
  - lookup_server_connector: 1.6.0
  - mail: 1.3.4
  - nextcloud_announcements: 1.7.0
  - notifications: 2.6.0
  - oauth2: 1.6.0
  - password_policy: 1.8.0
  - photos: 1.0.0
  - privacy: 1.2.0
  - provisioning_api: 1.8.0
  - recommendations: 0.6.0
  - serverinfo: 1.8.0
  - settings: 1.0.0
  - sharebymail: 1.8.0
  - support: 1.1.0
  - survey_client: 1.6.0
  - systemtags: 1.8.0
  - tasks: 0.12.2
  - text: 2.0.0
  - theming: 1.9.0
  - twofactor_backupcodes: 1.7.0
  - updatenotification: 1.8.0
  - viewer: 1.2.0
  - workflowengine: 2.0.0
Disabled:
  - admin_audit
  - encryption
  - files_external
  - user_ldap

Nextcloud configuration:

{
    "system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "itgenius.ru"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "dbtype": "mysql",
        "version": "18.0.4.2",
        "overwrite.cli.url": "https:\/\/itgenius.ru\/nextcloud",
        "htaccess.RewriteBase": "\/nextcloud",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "maintenance": false,
        "theme": "",
        "loglevel": 2,
        "updater.release.channel": "stable",
        "mail_smtpmode": "sendmail",
        "mail_sendmailmode": "smtp",
        "mail_from_address": "***REMOVED SENSITIVE VALUE***",
        "mail_domain": "***REMOVED SENSITIVE VALUE***",
        "mysql.utf8mb4": true
    }
}

Are you using external storage, if yes which one: no

Are you using encryption: no

Are you using an external user-backend, if yes which one: no

Client configuration

Browser: Firefox 75

Operating system: Ubuntu 18.04.4 LTS x64

CalDAV-clients: Web browser

Logs

Web server error log

No errors appears

Nextcloud log (data/nextcloud.log)

No log items when issue appears

Browser log

Console log
example.com-1588327616256.log

Network log
example.com.har.txt

[raimund-schluessler]

This is clearly a setup issue of your server, especially since you already figured out it is bypassed when you disable HTTP2. Tasks has nothing to do with the network protocol directly. We just send HTTP requests to the server and rely on them being properly answered.

Since this is a configuration issue of your server, please post this question in the forum: https://help.nextcloud.com

PS: I run Nextcloud and Tasks perfectly fine with HTTP2 enabled on Apache/2.4.29 (Ubuntu). Not sure how the older version Apache/2.4.7 you run behaves. Also your Ubuntu 16.04.1 is quite outdated as far as I know. Latest update to the 16.04. version is 16.04.6 (https://en.wikipedia.org/wiki/Ubuntu_version_history#1604). So I would recommend to update, at least to the latest patch level of 16.04.6.

[kain]

This is relatively big shared hosting, so unfortunately, I can't update it. I chatted in first place with hosting techsupport, and they assured me that server setup is OK.
I see some issues with HTTP/2 protocol in NC server part (nextcloud/server#16138), but guys direct me to Tasks for bug reporting (nextcloud/server#16138 (comment)).

@raimund-schluessler can you, please, check if 300 or more tasks work OK on your setup?

I exported my 300 test empty tasks (they can be imported via Calendar - Settings & Import)
testcal300.ics.zip

[raimund-schluessler]

@raimund-schluessler can you, please, check if 300 or more tasks work OK on your setup?

I exported my 300 test empty tasks (they can be imported via Calendar - Settings & Import)
testcal300.ics.zip

Did you try to import this ics file on your server? For me this fails with Calendar 2.0.3, might be a Calendar bug as well.

Probably because there are multiple VCALENDAR in the ics file.

[raimund-schluessler]

But I can tell you, that the app / config reproducible loads 443 completed tasks just fine.

[kain]

Thank you for support! Then I will configure test server on home computer with Ubuntu 18.04 and apache and test. Will post result here for future reference.

[raimund-schluessler]

What happens with the requests to the server? Do they succeed and return the correct number of tasks? If not, then it is a server and likely a config issue and we cannot do anything in the Tasks app.

[kain]

Some tasks load OK (207 HTTP code), some won't load (503 HTTP code). Which is which is random every page refresh.

[raimund-schluessler]

Well, if they randomly fail, especially with HTTP 503 (Service Unavailable), then it's definitely a server or config issue. These requests are handled by the CalDAV server which is part of Nextcloud server, so nothing we can do here, sorry. You should have a look at the server log, maybe it gives you a hint, why the requests fail. Also the Apache2 log might help here.

[kain]

Thanks @raimund-schluessler! I will try on local server, if issue are gone, then will change webhosting.