SubmitObserver does not exist

[Darren Grant]

I am using Magento 2.2.6 with the M2e extension that synchronises with ebay.

When an order comes in from ebay the following error is generated...

Magento Order was created successfully. However one or more post-processing actions on Magento Order failed. This may lead to some issues in the future. Please check the configuration of the ancillary services of your Magento. For more details, read the original Magento warning: Class Magento\Quote\Observer\Webapi\SubmitObserver does not exist.

I have tried contacting M2e about it but they are adamant that it is nothing to do with them and is a Magento problem. Any ideas?

Thanks

[Darren Grant · Accepted solution]

Found the solution myself

It seems that Webapi\SubmitObserver was moved or removed in Magento version 2.2.4. There was an out-of-date payment extension that still referenced this Observer that was causing M2epro to fail to update, even though they were completely unrelated. Changing the payment extension for an alternative newer version solved the problem for me. If anyone else runs into this problem check all your extensions. I feel that this change should not have been made in a minor point release but it is what it is.