In magento2 some times you may get following error message in log file. FastCGI sent in stderr: “PHP message: PHP Fatal error: Cannot declare class Namespace\Mymodule\Helper\Data because the name is already in use in Namespace/Mymodule/Helper/Data.php on line 10” while reading response header from upstream

Mean – You have used/declared Same class name for two different helper class in a file.

Ex: Actual Code:

namespace Namespace\Mymodule\Helper;
use Namespace\Mymodule1\Helper\Data
class Data extends \Magento\Framework\App\Helper\AbstractHelper
{
 public function __construct(
 Data $mymodule1helper
 ) {
 parent::__construct($context);
 }
}

Change it to as like below

namespace Namespace\Mymodule\Helper;
class Data extends \Magento\Framework\App\Helper\AbstractHelper
{
 public function __construct(
 Namespace\Mymodule1\Helper\Data $mymodule1helper
 ) {
 parent::__construct($context);
 }
}

I have used same class name for two different module Helper class (Data.php) in inside __construct().
To resolve this issue declare full class path from __construct.

 

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