One of the best feature in SharePoint is saving site as template is missing or some time you got error. I face this issue many time.
- if you enable Publishing features you can see save as template option in site settings.
- some time due to Custom features you can save site as Template. Especially SharePoint 2013 you will got error "Some thing went wrong you can not save site as template" in log you can see this type of error
its Difficult to identify what an issue , you have to go through the logs and based on Correlation ID you have to identify what's the error.
- if publishing feature is enable , and your are not using any publishing feature , disable it , after disable the feature you can see the "Save as Template " in site settings or
- if you require the Publishing feature then you can Edit the Url and add "/_layouts/15/savetmpl.aspx" at the end in SharePoint 2013 and add "_layouts/savetmpl.aspx" in SharePoint 2010. e.g http://myportal.com/sitea/_layouts/savetmpl.aspx
- using SharePoint Designer you can also change these settings. Open Site in SharePoint Designer , Default page at top right corner you can see the Site settings option , Click on it , and change SaveasTemplate value to true.