ValueError: imagecreatetruecolor(): Argument #1 ($width) must be greater than 0

[hardingt]

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Steps to reproduce

1. ui-bg_glass_55_fbf9ee_1x400 I found this in "css/jQuery/images/ui-bg_glass_55_fbf9ee_1x400.png" if it looks familiar to anyone.
2. Run the image preview generator app (I imagine if you look at the image it may cause the same error when the default app attempts to generate the preview): /var/www/nextcloud/occ preview:generate-all or /var/www/nextcloud/occ preview:generate-all -vvv app found here
3. You'll see the error:

Spoiler warning

ValueError: imagecreatetruecolor(): Argument #1 ($width) must be greater than 0 in 
/var/www/nextcloud/lib/private/legacy/OC_Image.php:926
Stack trace:
#0 /var/www/nextcloud/lib/private/legacy/OC_Image.php(926): imagecreatetruecolor()
#1 /var/www/nextcloud/lib/private/legacy/OC_Image.php(898): OC_Image->preciseResizeNew()
#2 /var/www/nextcloud/lib/private/legacy/OC_Image.php(1148): OC_Image->resizeNew()
#3 /var/www/nextcloud/lib/private/Preview/Generator.php(429): OC_Image->resizeCopy()
#4 /var/www/nextcloud/lib/private/Preview/Generator.php(186): OC\Preview\Generator->generatePreview()
#5 /var/www/nextcloud/lib/private/PreviewManager.php(205): OC\Preview\Generator->generatePreviews()
#6 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(203): OC\PreviewManager->generatePreviews()
#7 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(174): 
OCA\PreviewGenerator\Command\Generate->parseFile()
#8 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
#9 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
#10 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
#11 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
#12 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
#13 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
#14 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
#15 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(155): OCA\PreviewGenerator\Command\Generate->parseFolder()
#16 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(123): OCA\PreviewGenerator\Command\Generate->generateUserPreviews()
#17 /var/www/nextcloud/lib/private/User/Manager.php(610): OCA\PreviewGenerator\Command\Generate->OCA\PreviewGenerator\Command\{closure}()
#18 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(124): OC\User\Manager->callForSeenUsers()
#19 /var/www/nextcloud/3rdparty/symfony/console/Command/Command.php(255): OCA\PreviewGenerator\Command\Generate->execute()
#20 /var/www/nextcloud/3rdparty/symfony/console/Application.php(1009): Symfony\Component\Console\Command\Command->run()
#21 /var/www/nextcloud/3rdparty/symfony/console/Application.php(273): Symfony\Component\Console\Application->doRunCommand()
#22 /var/www/nextcloud/3rdparty/symfony/console/Application.php(149): Symfony\Component\Console\Application->doRun()
#23 /var/www/nextcloud/lib/private/Console/Application.php(215): Symfony\Component\Console\Application->run()
#24 /var/www/nextcloud/console.php(100): OC\Console\Application->run()
#25 /var/www/nextcloud/occ(11): require_once('...')

Expected behaviour

The width of the image is exactly 1, so the error of ($width) must be greater than 0 doesn't seem correct. Preview should generate or the error should be gracefully caught.

Actual behaviour

Preview generate ends in the above stacktrace

Server configuration

Operating system:
Ubuntu 20.04

Web server:
Apache/2.4.41

Database:
mysql Ver 8.0.23-0ubuntu0.20.04.1 for Linux on x86_64 ((Ubuntu))

PHP version:
Version: 8.0.3

Nextcloud version: (see Nextcloud admin page)
Nextcloud 21.0.0

Updated from an older Nextcloud/ownCloud or fresh install:
Fresh install of the www directory, the database is all the way back from version 12! (upgraded each few months). This is a brand new server though, so I ported over the db.

Where did you install Nextcloud from:
https://nextcloud.com/

Signing status:

Signing status

No errors have been found.

List of activated apps:

App list

Enabled:
  - accessibility: 1.7.0
  - activity: 2.14.3
  - cloud_federation_api: 1.4.0
  - comments: 1.11.0
  - contactsinteraction: 1.2.0
  - dashboard: 7.1.0
  - dav: 1.17.1
  - federatedfilesharing: 1.11.0
  - federation: 1.11.0
  - files: 1.16.0
  - files_pdfviewer: 2.1.0
  - files_rightclick: 1.0.0
  - files_sharing: 1.13.1
  - files_trashbin: 1.11.0
  - files_versions: 1.14.0
  - files_videoplayer: 1.10.0
  - firstrunwizard: 2.10.0
  - logreader: 2.6.0
  - lookup_server_connector: 1.9.0
  - nextcloud_announcements: 1.10.0
  - notifications: 2.9.0
  - oauth2: 1.9.0
  - password_policy: 1.11.0
  - photos: 1.3.0
  - previewgenerator: 3.1.1
  - privacy: 1.5.0
  - provisioning_api: 1.11.0
  - recommendations: 1.0.0
  - serverinfo: 1.11.0
  - settings: 1.3.0
  - sharebymail: 1.11.0
  - support: 1.4.0
  - survey_client: 1.9.0
  - systemtags: 1.11.0
  - text: 3.2.0
  - theming: 1.12.0
  - twofactor_backupcodes: 1.10.0
  - updatenotification: 1.11.0
  - user_status: 1.1.1
  - viewer: 1.5.0
  - weather_status: 1.1.0
  - workflowengine: 2.3.0
Disabled:
  - admin_audit
  - encryption
  - files_external
  - user_ldap

Nextcloud configuration:

Config report

{
    "system": {
        "instanceid": "***REMOVED SENSITIVE VALUE***",
        "passwordsalt": "***REMOVED SENSITIVE VALUE***",
        "secret": "***REMOVED SENSITIVE VALUE***",
        "trusted_domains": [
            "***REMOVED SENSITIVE VALUE***"
        ],
        "datadirectory": "***REMOVED SENSITIVE VALUE***",
        "overwrite.cli.url": "https:\/\/hardingt.duckdns.org\/",
        "dbtype": "mysql",
        "version": "21.0.0.18",
        "dbname": "***REMOVED SENSITIVE VALUE***",
        "dbhost": "***REMOVED SENSITIVE VALUE***",
        "dbport": "",
        "dbtableprefix": "oc_",
        "dbuser": "***REMOVED SENSITIVE VALUE***",
        "dbpassword": "***REMOVED SENSITIVE VALUE***",
        "installed": true,
        "maintenance": false,
        "updater.release.channel": "stable",
        "loglevel": 2,
        "theme": "",
        "mysql.utf8mb4": true,
        "memcache.local": "\\OC\\Memcache\\APCu",
        "default_phone_region": "US"
    }
}

Are you using external storage, if yes which one:
Nope

Are you using encryption:
No

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

Client configuration

Browser: N/A

Operating system: N/A

Logs

Web server error log

See below

Nextcloud log (data/nextcloud.log)

Nextcloud log

   ValueError: imagecreatetruecolor(): Argument #1 ($width) must be greater than 0 in 
   /var/www/nextcloud/lib/private/legacy/OC_Image.php:926
   Stack trace:
   #0 /var/www/nextcloud/lib/private/legacy/OC_Image.php(926): imagecreatetruecolor()
   #1 /var/www/nextcloud/lib/private/legacy/OC_Image.php(898): OC_Image->preciseResizeNew()
   #2 /var/www/nextcloud/lib/private/legacy/OC_Image.php(1148): OC_Image->resizeNew()
   #3 /var/www/nextcloud/lib/private/Preview/Generator.php(429): OC_Image->resizeCopy()
   #4 /var/www/nextcloud/lib/private/Preview/Generator.php(186): OC\Preview\Generator->generatePreview()
   #5 /var/www/nextcloud/lib/private/PreviewManager.php(205): OC\Preview\Generator->generatePreviews()
   #6 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(203): OC\PreviewManager->generatePreviews()
   #7 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(174): 
   OCA\PreviewGenerator\Command\Generate->parseFile()
   #8 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #9 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #10 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #11 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #12 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #13 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #14 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(172): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #15 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(155): OCA\PreviewGenerator\Command\Generate->parseFolder()
   #16 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(123): OCA\PreviewGenerator\Command\Generate->generateUserPreviews()
   #17 /var/www/nextcloud/lib/private/User/Manager.php(610): OCA\PreviewGenerator\Command\Generate->OCA\PreviewGenerator\Command\{closure}()
   #18 /var/www/nextcloud/apps/previewgenerator/lib/Command/Generate.php(124): OC\User\Manager->callForSeenUsers()
   #19 /var/www/nextcloud/3rdparty/symfony/console/Command/Command.php(255): OCA\PreviewGenerator\Command\Generate->execute()
   #20 /var/www/nextcloud/3rdparty/symfony/console/Application.php(1009): Symfony\Component\Console\Command\Command->run()
   #21 /var/www/nextcloud/3rdparty/symfony/console/Application.php(273): Symfony\Component\Console\Application->doRunCommand()
   #22 /var/www/nextcloud/3rdparty/symfony/console/Application.php(149): Symfony\Component\Console\Application->doRun()
   #23 /var/www/nextcloud/lib/private/Console/Application.php(215): Symfony\Component\Console\Application->run()
   #24 /var/www/nextcloud/console.php(100): OC\Console\Application->run()
   #25 /var/www/nextcloud/occ(11): require_once('...')

Browser log

N/A

[hardingt]

Looked into this a bit more, the GUI certainly shows that the image preview is blank. This appears to affect any abnormally tall or wide image, where a reduction in it's size may make an int round down to 0. Suggest fix is to make width and hight at least 1 when resizing.

[szaimen]

Is this Issue still valid in NC21.0.2? If not, please close this issue. Thanks! :)

[OneTwoBarbecue]

Actually this issue still occurs in NC 21.0.2 :(

[OneTwoBarbecue]

Issue still persists in NC 21.0.4
Any ideas on how to solve it or any workaround other than not running preview-generation?
Or may I support someone with further information?
Kind regards, Marco

[OneTwoBarbecue]

Workaround until resolved can be found here:
nextcloud/previewgenerator#252 (comment)