SessionHandler error

Same error here. It really seems to have happen randomly while browsing my website.
The only way to get it working back is by restarting my server, which would not be possible on a mutualized prod environment.

I'm seeing similar errors:

Fatal error: Class Drupal\\Core\\Session\\SessionHandler contains 2 abstract methods and must therefore be declared abstract or implement the remaining methods (SessionHandlerInterface::open, SessionHandlerInterface::read) in D:\\Apache24\\html\\core\\lib\\Drupal\\Core\\Session\\SessionHandler.php on line 15

Running Apache 2.4.18 from apachelounge and PHP 7.0.7.

As the original report states it seems to occur randomly.

Getting this one too. Not 100% sure but I think it happens when I open another session from another browser/device in the same network/same IP address as an already active session.

Fatal error: Class Drupal\Core\Session\SessionHandler contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (SessionHandlerInterface::open) in C:\xampp\apps\drupal\htdocs\core\lib\Drupal\Core\Session\SessionHandler.php on line 15

Running XAMPP on Windows with Apache 2.4.23, PHP 7, Drupal 8.2.3.

I got the same error after upgrading xampp from PHP 5.6.19 to 7.0.13

Fatal error: Class Drupal\Core\Session\SessionHandler contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (SessionHandlerInterface::read) in C:\Users\********\web\core\lib\Drupal\Core\Session\SessionHandler.php on line 15

I stopped getting that error once I moved from XAMPP to hosted environment (linux).

And now I got the second error of #7

PHP Fatal error:  Uncaught Error: Class 'Drupal\\Core\\Config\\DatabaseStorage' not found in C:\\Users\\***\\core\\lib\\Drupal\\Component\\DependencyInjection\\Container.php:272
Stack trace:
#0 C:\\Users\\***\\core\\lib\\Drupal\\Component\\DependencyInjection\\Container.php(509): Drupal\\Component\\DependencyInjection\\Container->createService(Array, 'private__757b70...')
#1 C:\\Users\\***\\core\\lib\\Drupal\\Component\\DependencyInjection\\Container.php(236): Drupal\\Component\\DependencyInjection\\Container->resolveServicesAndParameters(Array)
#2 C:\\Users\\***\\core\\lib\\Drupal\\Component\\DependencyInjection\\Container.php(177): Drupal\\Component\\DependencyInjection\\Container->createService(Array, 'config.storage')
#3 C:\\Users\\***\\core\\lib\\Drupal\\Component\\DependencyInjection\\Container.php(494): Drupal\\Component\\DependencyInjection\\Container->get('config.storage', 1)
#4 C:\\Users\\***\\core\\lib\\Drupal\\Component\\DependencyInjection\\Conta in C:\\Users\\***\\core\\lib\\Drupal\\Component\\DependencyInjection\\Container.php on line 272, referer: https://localhost/***

Two new observations:
1) After turning off opcache the "DatabaseStorage" error doesn't appear anymore
2) When the "abstract method" error occurs, it does on all Drupal installations on my localhost environment at the same time

Same issue,
1) After turning off opcache in php.ini. error doesn't appear anymore
2) updated d 8.2.2 to 8.2.6
3) after turning on opcache drupal works without errors/warnings

EDIT: 1 day after
Without any change in settings/modules/xampp error pops out:

Fatal error: Class Drupal\Core\Session\SessionHandler contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (SessionHandlerInterface::open) in C:\xampp\htdocs\test\core\lib\Drupal\Core\Session\SessionHandler.php on line 15
by the way: Error Log is empty.

I tried Flush all cashes and error disappeared.

I tried Flush all cashes and error disappeared.

Interesting, for me only restarting Apache works...

Same as Johnny83 in #16, restarting apache worked!

After Restarting Apache that issue fixed for me!

For me, this is happening on Drupal 8.2.3 and PHP 7.1.2 from XAMPP. This is not a Drupal-specific error, as other ecosystems see the Apache restart as a remedy, too: 1, 2, 3, 4, 5, 6, 7

Started working after restarting Apache :)

For me also after restarting Apache error is gone!

Restarting Apache fixed the issue.

After restarting Apache on Xampp this issue is gone.
I encounter this issue when adding image and clicking preview.

Restarting Xampp worked for me as well.

I get this error sometimes. My custom modules does call some external REST API and send back a Symfony Response object. Most of the times requests go through but sometimes i get "Fatal error: Class Drupal\Core\Session\SessionHandler" error.
Any one knows any relation of this error with Symfony API?

Same error here. It really seems to have happen randomly while browsing my website.
The only way to get it working back is by restarting my server, which would not be possible on fix this error.

affect to memory limit 254M ( memory_limit = 254M )
it is worked for me

I have the similar errors too. (Drupal 8.4.4)

Fatal error: Class Drupal\Core\Session\SessionHandler contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (SessionHandlerInterface::read) in C:\Apache24\htdocs\core\lib\Drupal\Core\Session\SessionHandler.php on line 15

Current my workaround: Disable "Page cache maximum age" by setting it

Drupal 8.4.4 + XAMP, when trying to uninstall a module got the same error :

Fatal error: Class Drupal\Core\Session\SessionHandler contains 1 abstract method and must therefore be declared abstract or implement the remaining methods (SessionHandlerInterface::open) in C:\mysites\htdocs\d8afsc\core\lib\Drupal\Core\Session\SessionHandler.php on line 15

After restarting XAMP apache and mysql, the site worked fine and I was able to uninstall the module.

I am convinced this is a bug in either PHP or Apache binaries. It cannot be solved within Drupal.

I found same kind of error and issue resolved after restarting my server but this is problematic while working on prod environment. Is there any proper solution rather than restart the server?

For me, disabling OPcache and restarting Apache worked but stopped working within an hour or so on a server that was being shared by multiple developers developing several different Drupal websites. We also made sure that PHP on this development server had access to plenty ram 3GB to be exact. This is also a CentOS 7 server running PHP 7.1 and Apache 2.4.

What ultimately worked for us was modify the OPcache settings... Here is what I changed:

• opcache.memory_consumption (increased from 128 to 256)
• opcache.interned_strings_buffer (increased from 8 to 16)
• opcache.max_accelerated_files (increased from 4000 to 8000)

Ultimately, I think the last one item is what did it for us. Drupal 8 has roughly 30,000 files in core alone, if PHP is only able to cache 4000 of those, there could be issues with dependencies being available at runtime.