PROBLEM
When you browse to the SharePoint Online or SharePoint Server Site settings page, you discover that the Save site as template option isn't available.MORE INFORMATION
This issue most frequently occurs because the Community Sites Feature site feature, the SharePoint Server Publishing site feature, or the SharePoint Server Publishing Infrastructure site collection feature is currently enabled or was previously enabled for the affected site.SharePoint doesn’t support creating a template from a site where publishing or community features were enabled. This is because the publishing feature creates site elements that are not supported as part of a template, and these elements remain even when the feature is disabled. This also includes templates that were created through SharePoint Designer.
Note Although the Save site as template option may become available after you deactivate publishing features, it is still unsupported to create a template from a site that has ever had publishing features enabled. If you create a site from this template, you may encounter problems when you try to activate publishing on the new site. For example, you may receive the following error message:
Provisioning did not succeed. Details: Failed to initialize some site properties for Web at Url: '......' OriginalException: Failed to compare two elements in the array.
In SharePoint Online, if you disabled scripting capabilities for the affected site, this also removes the Save site as template option.
For more information, go to the following Microsoft website:
Turn scripting capabilities on or off
Although you can't use the Save site as template option in this scenario, you can use the app model to customize the provisioning process in SharePoint Online or SharePoint Server 2013. This lets you enable specific features, capabilities, and branding for your sites.
For more information, go to the following Microsoft website:
Self-service site provisioning using Apps for SharePoint 2013
WorkAround / Solution
Save Site As Template In SharePoint Online
Notice anything missing from your Site Settings page recently? If you're in a SharePoint site on Office 365, Microsoft has quietly (with a loud response from the blogosphere) removed the Save Site as Template option. Using this classic option, which places a WSP file in the site collection's solution gallery, is supposed to provide an easy way for an end user to re-use the configuration of a site.Microsoft, as far as I know at this time, has yet to officially deprecate this functionality from SharePoint Online. It is still intact with SharePoint 2013.
They are hiding this from you for various technical reasons in favor of more sustainable site templating practices. I could explain them all if it wasn't mostly outside my wheelhouse... It has to do with SharePoint Apps, upgradability, etc. What matters at the moment for a site administrator is that there is currently no longer a user-accessible option to template a site, with or without content. Or is there?
Some posts are out there that describe adjusting or adding the SaveSiteAsTemplateEnabled property of the site to TRUE via PowerShell or SharePoint Designer. This appears to not be necessary except in the case of enabling SharePoint's publishing feature(s).
I conducted a test today on a plain site based on an OOTB team site template as well as a plain site based on an OOTB project site template. The page for saving a site as a template still exists if you append the following:
/_layouts/15/savetmpl.aspx
to the URL of your site. Voila! Your familiar page appears.
Reference:
A Quick Tip for Copying a Site in SharePoint Online
Save Site As Template In SharePoint Online
"Save site as template" option isn't available in SharePoint Online in Office 365 or SharePoint Server 2013