magento2: Upgrade to 2.2.1 from 2.1.2 fails with "Unable to serialize value" error

I have tried to upgrade to 2.2.1 from 2.1.2 version via composer upgrade. Upgrade was successful but when i try to open website frontend or backend, its showing “Unable to serialize value” error.

Preconditions

Magento 2.2.1
PHP 7.0

Steps to reproduce

Upgrade 2.1.2 version to latest 2.2.1 via composer
run upgrade command and deploy command

Expected result

All good but when we try to open website it throwing error There has been an error processing your request

Actual result

{"0":"Unable to serialize value.","1":"#0 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Translate.php(494): Magento\\Framework\\Serialize\\Serializer\\Json->serialize(Array)\n#1 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Translate.php(190): Magento\\Framework\\Translate->_saveCache()\n#2 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/App\/Area.php(244): Magento\\Framework\\Translate->loadData(NULL, false)\n#3 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/App\/Area.php(215): Magento\\Framework\\App\\Area->_initTranslate()\n#4 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/App\/Area.php(142): Magento\\Framework\\App\\Area->_loadPart('translate')\n#5 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/View\/DesignLoader.php(55): Magento\\Framework\\App\\Area->load('translate')\n#6 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/App\/Action\/Plugin\/Design.php(48): Magento\\Framework\\View\\DesignLoader->load()\n#7 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Interception\/Interceptor.php(121): Magento\\Framework\\App\\Action\\Plugin\\Design->beforeDispatch(Object(Magento\\Cms\\Controller\\Index\\Index\\Interceptor), Object(Magento\\Framework\\App\\Request\\Http))\n#8 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Interception\/Interceptor.php(153): Magento\\Cms\\Controller\\Index\\Index\\Interceptor->Magento\\Framework\\Interception\\{closure}(Object(Magento\\Framework\\App\\Request\\Http))\n#9 \/var\/www\/vhosts\/demo.com\/eiselec\/generated\/code\/Magento\/Cms\/Controller\/Index\/Index\/Interceptor.php(39): Magento\\Cms\\Controller\\Index\\Index\\Interceptor->___callPlugins('dispatch', Array, Array)\n#10 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/App\/FrontController.php(55): Magento\\Cms\\Controller\\Index\\Index\\Interceptor->dispatch(Object(Magento\\Framework\\App\\Request\\Http))\n#11 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Interception\/Interceptor.php(58): Magento\\Framework\\App\\FrontController->dispatch(Object(Magento\\Framework\\App\\Request\\Http))\n#12 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Interception\/Interceptor.php(138): Magento\\Framework\\App\\FrontController\\Interceptor->___callParent('dispatch', Array)\n#13 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/module-store\/App\/FrontController\/Plugin\/RequestPreprocessor.php(94): Magento\\Framework\\App\\FrontController\\Interceptor->Magento\\Framework\\Interception\\{closure}(Object(Magento\\Framework\\App\\Request\\Http))\n#14 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Interception\/Interceptor.php(135): Magento\\Store\\App\\FrontController\\Plugin\\RequestPreprocessor->aroundDispatch(Object(Magento\\Framework\\App\\FrontController\\Interceptor), Object(Closure), Object(Magento\\Framework\\App\\Request\\Http))\n#15 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/module-page-cache\/Model\/App\/FrontController\/BuiltinPlugin.php(73): Magento\\Framework\\App\\FrontController\\Interceptor->Magento\\Framework\\Interception\\{closure}(Object(Magento\\Framework\\App\\Request\\Http))\n#16 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Interception\/Interceptor.php(135): Magento\\PageCache\\Model\\App\\FrontController\\BuiltinPlugin->aroundDispatch(Object(Magento\\Framework\\App\\FrontController\\Interceptor), Object(Closure), Object(Magento\\Framework\\App\\Request\\Http))\n#17 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/Interception\/Interceptor.php(153): Magento\\Framework\\App\\FrontController\\Interceptor->Magento\\Framework\\Interception\\{closure}(Object(Magento\\Framework\\App\\Request\\Http))\n#18 \/var\/www\/vhosts\/demo.com\/eiselec\/generated\/code\/Magento\/Framework\/App\/FrontController\/Interceptor.php(26): Magento\\Framework\\App\\FrontController\\Interceptor->___callPlugins('dispatch', Array, NULL)\n#19 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/App\/Http.php(135): Magento\\Framework\\App\\FrontController\\Interceptor->dispatch(Object(Magento\\Framework\\App\\Request\\Http))\n#20 \/var\/www\/vhosts\/demo.com\/eiselec\/vendor\/magento\/framework\/App\/Bootstrap.php(256): Magento\\Framework\\App\\Http->launch()\n#21 \/var\/www\/vhosts\/demo.com\/eiselec\/index.php(39): Magento\\Framework\\App\\Bootstrap->run(Object(Magento\\Framework\\App\\Http))\n#22 {main}","url":"\/","script_name":"\/index.php"}

About this issue

Original URL
State: closed
Created 7 years ago
Comments: 22 (13 by maintainers)

Most upvoted comments

@speedupmate they are not supposed to detect anything, that’s why you need to assure you really convert serialized value at first place. It is guaranteed that upgrade script is executed only once thus double conversion won’t happen.

offers a way to store serialized arrays out of the box <backend_model>Magento\Config\Model\Config\Backend\Serialized\ArraySerialized</backend_model> then it should also be responsible for converting the values

Technically it is possible to find all such fields from module XMLs and convert them, but such mechanism would be too complicated and fragile. Also, don’t forget that Magento is highly customizable and there is no guarantee in particular store such model is not rewritten or there is no additional logic attached to stored data.

More specific, this is Case 6 of http://devdocs.magento.com/guides/v2.2/release-notes/backward-incompatible-changes.html#database-data-format-changes which is clearly documented and there is nothing to fix from core perspective.

orlangur on Jan 29, 2018

@orlangur let me argue a bit

Technically it is possible to find all such fields from module XMLs and convert them,

this is a simple foreach loop to find them by backend, since this is a core backend class its also a expected thing to cover those

be too complicated and fragile

try and catch to decode with json see if you get a valid config array back , if it fails try and catch with serialized array if it fails you output a reasonable error message to indicate that the format is not valid for this backend. Additional validation can be introduced etc.

there is no guarantee in particular store such model is not rewritten

what if it is not overwritten 😄 wonder what the odds are here vs reality. Currently m2 fails with hard exception without outputting a error message that is easy to get and sort out. That certainly is a better thing than the chance of this class being overwritten. The set of functionality that causes the issue does not even exist in older version.

More specific, this is Case 6

I agree and already provided a upgrade script to our customers just to move on , however this case does not have to exist at all since considered functionality is covered with core functionality that all extension providers can relay on.

speedupmate on Jan 30, 2018