Experts at https://ecomitize.com/ recommend following these instructions:
Delete the generated / code directory rm -rf generated / code
php bin / magento setup: upgrade
php bin / magento setup: di: compile
php bin / magento cache: flush
chmo -R 0777 var / pub / generated /
Hopefully it helps.
Message "There has been an error processing your request. Exception printing is disabled by default for security reasons." is a very common problem, which usually appear after update (Magento 2 or extension) or changes in templates code.
For security reasons, Magento 2 hides a full error message and shows the message above with "Error log record number" reference.