Error while migrating Bitrix site, what's the problem?

Question

1C-Bitrix

Hello!

When transferring the site to vps, the following error occurred, what could be the problem, please tell me.

[Error]
Class '....\Helper' not found (0)
/home/bitrix/ext_www/site/local/templates/main/header.php:103
#0: include_once
/home/bitrix/ext_www/site/ bitrix/modules/main/include/prolog_after.php:106
#1: require(string)
/home/bitrix/ext_www/site/bitrix/modules/main/include/prolog.php:11
#2: require_once(string)
/ home/bitrix/ext_www/site/bitrix/header.php:3
#3: require(string)
/home/bitrix/ext_www//index.php:2