If you experience a “500 Internal Server Error” when trying to export or import templates, this is most likely due to the content of the page overloading your server when trying to export.
The most common cause for this is very large images used on the page.
You should ensure all images used on your page are optimized for web usage – this means they should be no larger than 500kb-1mb maximum (smaller if possible) and you should also run them through a compression tool like Tinypng to assist with optimizing for web
As a general rule of thumb, any image used on a web page should be no larger than 2x (2 times) the size it is embedded on the page. So if you use an image on the page which is set to 500px width then you should ensure the image width is no larger than 1000px width total.