Home page of the sub site throwing error:

Issue : Home page of the sub site throwing error: "The site is not valid. The 'Pages' document library is missing. "

Reason: This error is thrown because the pages library’s ID was abnormally corrupted due to forceful activation of the Publishing Feature at site level.

Solution: Assign a new ID to the pages library. Powershell command to accomplish this is below.

$web = get-spweb <Site URL>
$correctId = $web.Lists["Pages"].ID
$web.AllProperties["__PagesListId"] = $correctId.ToString()
$web.Update()
$web.AllProperties["__PublishingFeatureActivated"] = "True"
$web.Update()