Failed to save data for template id – Umbraco
You came to this error without having idea what went wrong. You do not have an idea where to start digging. And you are the most probably on production environment. Production only bugs , like nightmare, are part of your life. On the other side your development environment still rocks. You do not have an idea what is going wrong between environments. Furthermore, production logs seems quite unhelpful. Nothing appears there. Log files simply do not understand your pain.
Wait a bit, for a Good sake, what might be wrong? You got ghost on production server or something else. You never know :). In my case, this was the case: somehow file/folder access rights came across change and removed modify rights for my App pool. Simply grant full access rights to AppData folder immediately resolved the issue.
Here you can see how that looks like on Plesk.
At the end we all should admit the error description may be more detailed and directs toward access rights issues.
So, it might be worth to check some trivial obstacles like access rights while you next time get generic errors like this one.
After you fix this issue I can only wish you happy coding, deploying, bug fixing… 🙂
And the last, but not the least, link below contains access setup rules that is worth to follow https://our.umbraco.com/documentation/Getting-Started/Setup/Server-Setup/permissions . This may ensure your environment avoid trivial pitfalls and leave you more time doing interesting stuff.