Payment Gateway CcAvenue is not redirecting to Website on Magento 2.2.6

[ratan_yadav]

Hi , 

I am using Magento version 2.2.6 . Here I have integrated the Ccavenue payment Gateway and disabled Paypal .
When frontend is placing order then payment happens successful but while payment gateway redirecting back to website , I  get below Error . 

Fatal error: Uncaught TypeError:
 Argument 1 passed to Magento\Paypal\Model\Adminhtml\Express::isOrderAuthorizationAllowed()
 must be an instance of Magento\Sales\Model\Order\Payment, null given, 
 called in /home/xxxxxxxx/public_html/vendor/magento/module-paypal/Plugin/OrderCanInvoice.php on line 41 and 
 defined in /home/xxxxxxxx/public_html/vendor/magento/module-paypal/Model/Adminhtml/Express.php:169 
 Stack trace: 
 #0 /home/xxxxxxxx/public_html/vendor/magento/module-paypal/Plugin/OrderCanInvoice.php(41):
 Magento\Paypal\Model\Adminhtml\Express->isOrderAuthorizationAllowed(NULL)
 #1 /home/xxxxxxxx/public_html/vendor/magento/framework/Interception/Interceptor.php(146):
 Magento\Paypal\Plugin\OrderCanInvoice->afterCanInvoice(Object(Magento\Sales\Model\Order\Interceptor), false) 
 #2 /home/xxxxxxxx/public_html/vendor/magento/framework/Interception/Interceptor.php(153): 
 Magento\Sales\Model\Order\Interceptor->Magento\Framework\Interception\{closure}()
 #3 /home/xxxxxxxx/public_html/generated/code/Magento/Sales/Model/Order/Interceptor.php(26):
 Magento in /home/xxxxxxxx/public_html/vendor/magento/module-paypal/Model/Adminhtml/Express.php on line 169

Searched alot on Web but could not understand whats going wrong . Any help on this regard is highly appreciable . 

[Sanjay Jethva]

@ratan_yadav 

Try to check by disabling other third-party extensions one by one as it's strange that it shows PayPal's error in Ccavenue!

It might be possible that another third-party module is causing an issue.

[ratan_yadav]

Hi Sanjay , 

Thanks for response but when I disable paypal then my payment gatway itself is not working . 

I am not sure if CCAvenue is being called through paypal or what ?

My Error is for second payment onwards , first payment is always success .