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[5.x]: Changes to the project config are not possible while in read-only mode when viewing updates #17750

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#19546
Open
[5.x]: Changes to the project config are not possible while in read-only mode when viewing updates#17750
#19546
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bug

Description

@Thijmen
Thijmen
opened on Aug 16, 2025

What happened?

Description

I tried to view the Updates section in the Utilities panel, got an error that fetching updates was not possible.

In my logs I get Changes to the project config are not possible while in read-only mode.

Steps to reproduce

  1. Run Craft 5.8.15 in production mode and visit the updates page

Expected behavior

Potential updates are visible

Actual behavior

Error is being shown

Craft CMS version

5.8.15

PHP version

No response

Operating system and version

No response

Database type and version

No response

Image driver and version

No response

Installed plugins and versions

Activity

  1. Thijmen
    added
    bug
    on Aug 16, 2025

  2. linear commented on Aug 16, 2025

    @linear
    linearBot
    on Aug 16, 2025 – with Linear

    CMS-1546 [5.x]: Changes to the project config are not possible while in read-only mode when viewing updates

  3. brandonkelly commented on Aug 17, 2025

    @brandonkelly
    brandonkelly
    on Aug 17, 2025
    Member

    Can you post the full stack trace for the error from your logs?

  4. Thijmen commented on Aug 19, 2025

    @Thijmen
    Thijmen
    on Aug 19, 2025
    Author

    Hmm, seems I cannot reproduce this anymore, currently on 5.8.15. Only see some plugin updates, perhaps it behaves different when there is a Craft update but I doubt it. Will report back when there is a new Craft update and will close it if the issue is gone.

  5. Thijmen commented on Sep 1, 2025

    @Thijmen
    Thijmen
    on Sep 1, 2025
    Author

    I got it again, let me know what I can do to help.

    {
  "trace": [
    "#0 /cms/app/vendor/craftcms/cms/src/services/ProjectConfig.php(526): craft\\services\\ProjectConfig->_setInternal()",
    "#1 /cms/app/vendor/craftcms/cms/src/services/Plugins.php(1193): craft\\services\\ProjectConfig->set()",
    "#2 /cms/app/vendor/craftcms/cms/src/helpers/Api.php(203): craft\\services\\Plugins->setPluginLicenseKey()",
    "#3 /cms/app/vendor/craftcms/cms/src/controllers/AppController.php(172): craft\\helpers\\Api::processResponseHeaders()",
    "#4 [internal function]: craft\\controllers\\AppController->actionProcessApiResponseHeaders()",
    "#5 /cms/app/vendor/yiisoft/yii2/base/InlineAction.php(57): call_user_func_array()",
    "#6 /cms/app/vendor/yiisoft/yii2/base/Controller.php(178): yii\\base\\InlineAction->runWithParams()",
    "#7 /cms/app/vendor/yiisoft/yii2/base/Module.php(552): yii\\base\\Controller->runAction()",
    "#8 /cms/app/vendor/craftcms/cms/src/web/Application.php(360): yii\\base\\Module->runAction()",
    "#9 /cms/app/vendor/craftcms/cms/src/web/Application.php(659): craft\\web\\Application->runAction()",
    "#10 /cms/app/vendor/craftcms/cms/src/web/Application.php(322): craft\\web\\Application->_processActionRequest()",
    "#11 /cms/app/vendor/yiisoft/yii2/base/Application.php(384): craft\\web\\Application->handleRequest()",
    "#12 /cms/app/web/index.php(21): yii\\base\\Application->run()",
    "#13 {main}"
  ],
  "memory": 8923440,
  "exception": "[object] (yii\\base\\NotSupportedException(code: 0): Changes to the project config are not possible while in read-only mode. at /cms/app/vendor/craftcms/cms/src/services/ProjectConfig.php:554)"
}

    Looks to me that there is a plugin without a license key? We have a plugin that's internal, not via the plugin store though. Is this something wrong on our end?

  6. Thijmen commented on Sep 1, 2025

    @Thijmen
    Thijmen
    on Sep 1, 2025
    Author

    Well, I re-installed Blitz few commits ago and it did not generate the licenseKey in the YAML - mistake on my end. But perhaps this can also be prevented in the future?

  7. jamesevans1808 commented on May 28, 2026

    @jamesevans1808
    jamesevans1808
    on May 28, 2026

    I recently encountered this issue whilst upgrading a Craft 5 to 5.10.3 from v 5.9.20. Here is my stacktrace according to the error logs:

    2026-05-27 14:07:23 [web.INFO] [craft\db\MigrationManager::migrateUp] Applying m260401_155236_min_authors_setting {"memory":4097896} 
2026-05-27 14:07:23 [web.ERROR] [craft\db\MigrationManager::migrateUp] Failed to apply m260401_155236_min_authors_setting (time: 0.196s). Output:
    > add column minAuthors smallint UNSIGNED NOT NULL DEFAULT 1 AFTER `enableVersioning` to table {{%sections}} ... done (time: 0.169s)
Exception: Changes to the project config are not possible while in read-only mode. (/var/www/html/vendor/craftcms/cms/src/services/ProjectConfig.php:556)
#0 /var/www/html/vendor/craftcms/cms/src/services/ProjectConfig.php(528): craft\services\ProjectConfig->_setInternal()
#1 /var/www/html/vendor/craftcms/cms/src/services/Entries.php(608): craft\services\ProjectConfig->set()
#2 /var/www/html/vendor/craftcms/cms/src/migrations/m260401_155236_min_authors_setting.php(29): craft\services\Entries->saveSection()
#3 /var/www/html/vendor/craftcms/cms/src/db/Migration.php(50): craft\migrations\m260401_155236_min_authors_setting->safeUp()
#4 /var/www/html/vendor/craftcms/cms/src/db/MigrationManager.php(233): craft\db\Migration->up()
#5 /var/www/html/vendor/craftcms/cms/src/db/MigrationManager.php(149): craft\db\MigrationManager->migrateUp()
#6 /var/www/html/vendor/craftcms/cms/src/services/Updates.php(246): craft\db\MigrationManager->up()
#7 /var/www/html/vendor/craftcms/cms/src/controllers/BaseUpdaterController.php(498): craft\services\Updates->runMigrations()
#8 /var/www/html/vendor/craftcms/cms/src/controllers/UpdaterController.php(195): craft\controllers\BaseUpdaterController->runMigrations()
#9 [internal function]: craft\controllers\UpdaterController->actionMigrate()
#10 /var/www/html/vendor/yiisoft/yii2/base/InlineAction.php(60): call_user_func_array()
#11 /var/www/html/vendor/yiisoft/yii2/base/Controller.php(182): yii\base\InlineAction->runWithParams()
#12 /var/www/html/vendor/yiisoft/yii2/base/Module.php(547): yii\base\Controller->runAction()
#13 /var/www/html/vendor/craftcms/cms/src/web/Application.php(368): yii\base\Module->runAction()
#14 /var/www/html/vendor/craftcms/cms/src/web/Application.php(728): craft\web\Application->runAction()
#15 /var/www/html/vendor/craftcms/cms/src/web/Application.php(257): craft\web\Application->_processUpdateLogic()
#16 /var/www/html/vendor/yiisoft/yii2/base/Application.php(382): craft\web\Application->handleRequest()
#17 /var/www/html/web/index.php(21): yii\base\Application->run()
#18 {main}
 {"memory":4332704} 
2026-05-27 14:07:23 [web.ERROR] [craft\db\MigrationManager::up] Migration failed. The rest of the migrations are cancelled. {"memory":4338920} 
2026-05-27 14:07:23 [web.ERROR] [craft\controllers\BaseUpdaterController::runMigrations] craft\migrations\m260401_155236_min_authors_setting migration failed: Changes to the project config are not possible while in read-only mode. {"memory":4333640} 
2026-05-27 14:07:23 [web.ERROR] [yii\base\NotSupportedException] yii\base\NotSupportedException: Changes to the project config are not possible while in read-only mode. in /var/www/html/vendor/craftcms/cms/src/services/ProjectConfig.php:556

    It also appears to apply some migrations, fails at this one in particular, which then leaves the database in a partially migrated state, meaning it now fails due to "duplicate columns" that were created earlier in the migration and not reverted by the Migrate tool that appears when you go to /admin after deployment. This means we then have to put a DB backup in place and revert.

    If we run the deployment with admin changes allowed, we don't get the problem, which seems counterintuitive, as surely deployment and applying of updated composer and yaml files should allow for Db changes without being beholden to this setting.

  8. brandonkelly commented on May 28, 2026

    @brandonkelly
    brandonkelly
    on May 28, 2026
    Member

    @jamesevans1808 The expectation is that you first update Craft on a local environment where admin changes are allowed. If you are updating via Composer, ensure you always run craft up after the update so any pending migrations are run.

    Then you commit your composer.json + composer.lock changes with any changes within config/project/, and deploy all those changes together.

    If you deploy the project config changes along with the Composer changes, then you won’t hit that error when migrations are run on production.

    It also appears to apply some migrations, fails at this one in particular, which then leaves the database in a partially migrated state, meaning it now fails due to "duplicate columns" that were created earlier in the migration and not reverted by the Migrate tool that appears when you go to /admin after deployment. This means we then have to put a DB backup in place and revert.

    Yes, that’s expected.

  9. jamesevans1808 commented on May 28, 2026

    @jamesevans1808
    jamesevans1808
    on May 28, 2026 via email

  10. brandonkelly commented on May 28, 2026

    @brandonkelly
    brandonkelly
    on May 28, 2026
    Member

    @jamesevans1808 Do you have a database backup from Craft 5.9.20? If so can you please send that, along with the composer.json + composer.lock files and project config files you deployed (post-local 5.10 upgrade) over to support@craftcms.com?

  11. jamesevans1808 commented on May 29, 2026

    @jamesevans1808
    jamesevans1808
    on May 29, 2026

    @brandonkelly we're unable to send a database backup, as that would be a breach of GDPR. Looking at my notes, here is the complete process we did for the relevant upgrades that failed for us:

    • Logged into the CMS, navigated to the Updates utility
    • Pressed the "Update all" button
    • Waiting for the process to finish
    • Pressed the "Finish Up" button to apply database changes
    • Committed all the files that were changed. No yaml changes were present in these instances after using the Upgrade utility.
    • Deployed to a test environment using Deployer 7.2
    • Navigated to /admin
    • Pressed the "Finish Up" button to apply database changes
    • Fails due to Read-Only
    • SSH to test environment, alter general.php config to allowAdminChanges => true
    • Pressed the "Finish Up" button to apply database changes
    • Fails due to duplicate columns as shown in previous stack trace

    Hope that helps.

  12. brandonkelly commented on Jun 1, 2026

    @brandonkelly
    brandonkelly
    on Jun 1, 2026
    Member

    No yaml changes were present in these instances after using the Upgrade utility.

    That should definitely not have been the case when upgrading from 5.9 to 5.10, as 5.10 included new migrations, which would at the least update the dateModified and system.schemaVersion values.

  13. mvanhorn
    added a commit that references this issue on Sep 3, 2026

    fix: Skip automatic plugin license writes in read-only mode

    e1ae327
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