SharePoint Online - create new subsite error

Trying to create a new sub-site using our custom template received an error, MobileExcelWebAccess Feature Site Collection is not enabled. See captured screen below. Microsoft actually posted a blog about "Depreciation of Custom Code in Sandboxed Solutions". I don't know about you but I did not get this notice. Anyway, they basically disabled this feature for custom template without providing alternative solutions. I have provided a step-by-step guide on how to enable it but note Microsoft highly recommended to use their existing template and work your way to support project needs. First two steps, download and install these tools. 1) Install SharePoint Online Management Shell from the below download link https://www.microsoft.com/en-us/download/details.aspx?id=35588 2) Install The SharePoint Online Client Components SDK from the below download link https://www.microsoft.com/en-in/download/details.aspx?id=42038 Double check if you have a SharePoint permission to access the site. This is to make sure the username and password that you will use has permission. Once completed, search for Windows Powershell ISE, right click on to run as Administrator. Use the following script below to execute. Change the SharePoint admin link using your own e.g I use https://KINGdotNET-admin.sharepoint.com -credential [email protected]. Simply change KINGdotNET using your domain and the username. Two lines at the end, you need to change "YourPassword" with your account password with permission to access the site.

Connect-SPOService -Url https://KINGdotNET-admin.sharepoint.com -credential [email protected] $host.Runspace.ThreadOptions = "ReuseThread" #Definition of the function that allows to enable a SPO Feature function Enable-SPOFeature { param ($sSiteColUrl,$sUserName,$sPassword,$sFeatureGuid) try { #Adding the Client OM Assemblies Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.dll" Add-Type -Path "C:\Program Files\Common Files\microsoft shared\Web Server Extensions\16\ISAPI\Microsoft.SharePoint.Client.Runtime.dll" #SPO Client Object Model Context $spoCtx = New-Object Microsoft.SharePoint.Client.ClientContext($sSiteColUrl) $spoCredentials = New-Object Microsoft.SharePoint.Client.SharePointOnlineCredentials($sUsername, $sPassword) $spoCtx.Credentials = $spoCredentials Write-Host "----------------------------------------------------------------------------"  -foregroundcolor Green Write-Host "Enabling the Feature with GUID $sFeatureGuid !!" -ForegroundColor Green Write-Host "----------------------------------------------------------------------------"  -foregroundcolor Green $guiFeatureGuid = [System.Guid] $sFeatureGuid $spoSite=$spoCtx.Site $spoSite.Features.Add($sFeatureGuid, $true, [Microsoft.SharePoint.Client.FeatureDefinitionScope]::None) $spoCtx.ExecuteQuery() $spoCtx.Dispose() } catch [System.Exception] { write-host -f red $_.Exception.ToString() } } #Required Parameters $sSiteColUrl = "https://KINGdotNET.sharepoint.com/proposalservices" $sUserName = "[email protected]" $sFeatureGuid= "e995e28b-9ba8-4668-9933-cf5c146d7a9f" $sPassword = Read-Host -Prompt "Enter your password: " -AsSecureString $sPassword=convertto-securestring "YourPassword" -asplaintext -force Enable-SPOFeature -sSiteColUrl $sSiteColUrl -sUserName $sUserName -sPassword $sPassword -sFeatureGuid $sFeatureGuid

  If you execute the script without error, you should be able to create a sub-site using a custom template.

I hope this save you some time. KINGdotNET
Source: http://www.king.net/sharepoint-online-create-new-subsite-error/