If after updating Magento (Adobe Commerce) to version 2.4.4 and higher your customers receive order emails without a list of products, then the solution below should help you solve your problem.
Firs
If you can't log in to the admin panel, but no error is shown, then you may have a problem with the session size.
Below is one solution to this problem.
If you have the error as in the title of this page this solution can help you.
In our case, this error happened when we synchronize live DB in dev DB.
The solution
Before anything action, you must
If after running the command php bin / magento setup: di: compile your proxy class was not created, then a possible reason may be that your di.xml has line breaks in the "argument" field.
