Hi,
This is just a warning and not a consequence.
However, this could be an error or a missing item in language file:
wamp(64)\lang\modules\settings_english.php
In the Right-Click -> Wamp settings menu, is there an item :
Backup hosts file
If no, check in file wamp(64)\lang\modules\settings_english.php if there is for the array $w_settings:
.....
'BackupHosts' => 'Backup hosts file',
If so, this shows that the corresponding index does not exist in your language file if you use a language other than English.
It could also be that there is an algorithm flaw in the loading of language files because if an index does not exist in the language file used, then the index of the English language file is used.
Ignore this warning until the next update of Wampserver which should fix this defect.
---------------------------------------------------------------
Documentation Apache -
Documentation PHP -
Documentation MySQL -
Wampserver install files & addons