Execution of /usr/local/psa/bin/domain_pref --update <domain> -at-access true failed

[speedy]

In case someone is interested: If you use the migration manager and you receive an error like:

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Execution of /usr/local/psa/bin/domain_pref --update <domain> -at-access true failed with return code 1.
Stderr is filemng: Unable to recieve real path for '/var/www/vhosts/<domains>/httpdocs/at_domains_index.html'
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do the following to fix it:

1. Make sure the at_domains_index.html is on the 'old' server in http(s)docs
2. Go to web_users and then preferences
3. Uncheck the option "Enable webuser@<domain> access format
4. Make sure the at_domains_index.html is gone in http(s)docs
5. Migrate the domain without errors :-)

And if you need to enable the option mentioned in (3) again, just copy the at_domains_index.html to the http(s)docs and check the option "Enable webuser@<domain> access format under preferences of web_users