Just that. After update the system from 3.0 to 3.1.2.1 I have a blank page and this error. Any help? thanks in advance, solve this is kinda critical for me.
I have this entries on error_log
[21-Oct-2019 03:57:38 UTC] PHP Warning: Declaration of CustomBlockPlugin::getBlockContext() should be compatible with BlockPlugin::getBlockContext($contextId = NULL) in /plugins/generic/customBlockManager/CustomBlockPlugin.inc.php on line 134
[21-Oct-2019 03:57:38 UTC] PHP Warning: Declaration of CustomBlockPlugin::getBlockContext() should be compatible with BlockPlugin::getBlockContext($contextId = NULL) in /plugins/generic/customBlockManager/CustomBlockPlugin.inc.php on line 134
[21-Oct-2019 03:57:38 UTC] PHP Warning: Declaration of QuickSubmitPlugin::register($category, $path) should be compatible with Plugin::register($category, $path, $mainContextId = NULL) in /plugins/importexport/quickSubmit/QuickSubmitPlugin.inc.php on line 248
[21-Oct-2019 03:57:38 UTC] PHP Warning: Declaration of QuickSubmitPlugin::smartyPluginUrl($params, &$smarty) should be compatible with Plugin::smartyPluginUrl($params, $smarty) in /plugins/importexport/quickSubmit/QuickSubmitPlugin.inc.php on line 248
You should find another line in the error log which describes a “PHP Error” or “PHP Fatal”. These “PHP Warning” messages are almost never the source of a blank white screen.
Did you upgrade the QuickSubmit plugin at the same time as the upgrade to 3.1.2? If not, be sure to visit the plugin gallery to update any plugins (or perform these upgrades manually).
I made the upgrade as its described on the docs. I need to upgrade the plugin manually? Can I change the complete folder of the plugin for the new one ?
Which option in the documentation did you use for the upgrade?
The full package download does not include the QuickSubmit plugin. It is expected to be installed via the Plugin Gallery.
If you used a git-based upgrade, you will need to upgrade the QuickSubmit plugin as well.
The typical way to upgrade the plugin will be through the Plugin Gallery, but if you used a git-based upgrade for the application, you may want to do the same manually for the plugin(s).
I downloaded the full package. But after that I tried to upload a new version of the plugin and it does nothing. What version is the appropriate?
Regards
Are you able to use the Plugin Gallery to install the plugin? It will automatically select the best version.
If you cannot use the Plugin Gallery, you will want to find a plugin release which describes support for your version of OJS.
For the QuickSubmit plugin, the releases are here:
For OJS 3.1.2-1, the latest compatible release is v1.0.4-1.
yes. I tried that but the plugin doesn’t work anyway 
This issue can be related with permissions ?
Installing plugins via the Plugin Gallery requires that your webserver have permissions to write to the filesystem under the plugins/ folder. This may be disabled for security reasons. If you do not want to allow the webserver to write to the plugins folder, you can still install the plugin manually by copying the files into the filesystem. This requires care in identifying which version to select and care in place the folder in the correct place with the correct name.
What error (PHP error or PHP fatal) are you currently seeing in your PHP error log when you try to use the QuickSubmit plugin?
I get this:
PHP Fatal error: Uncaught Error: Call to a member function getCoverImage() on /plugins/importexport/quickSubmit/QuickSubmitForm.inc.php:116