The serialiser doesn't work since version 3.16.0

[CJDennis]

Q	A
Bug report?	yes
Feature request?	no
BC Break report?	yes
RFC?	no

#1366 added the following lines to src/Metadata/ClassMetadata.php:

            $this->discriminatorGroups,
            $this->xmlDiscriminatorAttribute,
            $this->xmlDiscriminatorCData,
            $this->usingExpression,
            $this->xmlDiscriminatorNamespace,
            $this->xmlRootPrefix,
            $this->isList,
            $this->isMap,

I now get [PHPUnit\Framework\Error\Warning] Undefined array key 16 at vendor\jms\serializer\src\Metadata\ClassMetadata.php:322 when running tests since $this->discriminatorGroups (which is already included two lines above) does not exist in the array.

Steps required to reproduce the problem

1. Use any version from 3.16.0 to 3.18.2
2. Serialise some data

Expected Result

• The data is serialised.

Actual Result

• An error 500 in production mode.
• [PHPUnit\Framework\Error\Warning] Undefined array key 16 in tests.

[goetas]

please clear the cache

[eloirobe]

I've cleared the cache, both using the command clear:cache and deleting it completely by removing the whole folder, and it still doesn't work. I did some checks and I believe it crashes in JMS\Serializer\Metadata\ClassMetadata.php, method unserializeFromArray. When we check the values inside the param $data, we see the current values:

[scyzoryck]

Hi! Are you using JMSSerializerBundle ? What is yours cache configuration?

[eloirobe]

Yes we're using JMSSerializerBundle
This is the Cache config with memcached also we clear memcached and not work:

framework:
    cache:
        default_memcached_provider: "%memcached.parameters%"
        pools:
            doctrine.result_cache_pool:
                adapter: cache.adapter.memcached
            doctrine.system_cache_pool:
                adapter: cache.adapter.memcached
            doctrine.second_level_cache_pool:
                adapter: cache.adapter.memcached
            doctrine.main_cache_region_pool:
                adapter: cache.adapter.memcached

[eloirobe]

Now it works We upgrade the JMSSerializerBundle from 3.9.x to version 4.0.x and it works. Is it possible that JMSSerializerBundle doesn't had well configure the require version of JMSSerializer in version 3.9.x?

[goetas]

Please make sure to clean the cache (whatever cache you might be using, files, redis, apc...)