Fatal error after upgrade from 2.1.8 to 2.2.0

Question

I was running 2.1.8 (or if it was 2.1.9) and decided to upgrade. After some errors (documented at gitHub), I was able to run php bin/magento setup:upgrade. It tells me to run bin/magento setup:di:compile, which I did.

It throws the following error:

Fatal error:  Class MagePal\GmailSmtpApp\Model\Transport contains 1 
abstract method and must therefore be declared abstract or implement 
the remaining methods (Magento\Framework\Mail\TransportInterface::getMessage) 
in /opt/bitnami/apps/magento/htdocs/app/code/MagePal/GmailSmtpApp/Model/Transport.php 
on line 11

I tried clearing the different var-directories (when in my magento-root), with

rm -rf ./var/di/* ./var/view_preprocessed/* ./var/generation/* 
./var/composer_home/* ./var/cache/* ./var/page_cache/*

I've reset the permissions of the owner according to the manual at bitnami (this is the image I run, on a Google cloud instance).

I also looked into the transport.php-file. This didn't implement the getMessage()-function. So I used composer to get the latest (composer require magepal/magento2-gmailsmtpapp), I copied the complete folder into the app/code/-directory instead, as it was where I originally had it. Then, I removed it with composer (composer remove magepal/magento2-gmailsmtpapp). I again clean the different var-directories. I then run the magento setup:upgrade-command and magento setup:di:compile-command again. It throws the same error. For reference, the transport.php-file looks like this. This is one solution to the issue, I just messed up the copying (see below answer).

Sometimes, there is also a note about Segmentation fault. However, it seems to disappear after I've runned the setup:di:compile a couple of times, I also read about setting "ulimit -s 65536", it doesn't help.

The only thing I've been able to do, to get it up and running again is to rollback backups into a clean 2.1.9-installation.

Any advice would be very appreciated. Thanks.

Answer 1

I fixed the issue.

The root cause was that the app/code/MagePal/GmailSmtpApp-module wasn't updated when I used the web upgrade. My Magento-installation still contained old files. The error message is clear, one function / method missing (in the implementation of the abstract class). To fix this, I went ahead and thought I was replacing the old module with the new one (I used composer, composer require magepal/magento2-gmailsmtpapp, moved those files, and then used composer to remove it again, composer remove magepal/magento2-gmailsmtpapp).

What went wrong?

• I copied the content of /GmailSmtpApp/* to /MagePal/. Instead, I should have copied the content of newmodulelocation/MagePal/* to /MagePal/
• The old files were loaded and error still valid.

How to discover or debug a similar issue?

• Search for some unique content of the first file. If found, investigate those files.
• With linux-system, you search with the following command: sudo grep -r "Mail Transport"

Now, I only have other errors. I assume those are unrelated. If not, I'll come back.

Answer 2

put following function inside your app/code/MagePal/GmailSmtpApp/Model/Transport.php

/**
 * @inheritdoc
 */
public function getMessage()
{
    return $this->_message;
}

This is working solution for me.

I hope it will help you too :)