Even on SharePoint Online, it’s now more and more important for companies to brand their sites.
So you might need to use the SharePoint Style Library in order to store your style documents.
But in Office 365 if you don’t activate the feature of “Custom Script” you won’t be able to edit, create or upload document(s) into the Style Library.
You will then figure issues, such as the one illustrated below:
“Sorry, your files couldn’t be uploaded. The upload might be too large or the server might be experiencing high network traffic.”
having “You don’t have permission to perform this action” error message, even if you’re tenant administrator!
I agree those error messages are not really meaning full, if you know to what they are related.
To solve this issue:
- Go to your SharePoint Admin Center (https://MYTENANT-admin.sharepoint.com)
- Go to the settings menu
- Scroll down until you see the “Custom Script” menu
- Allow users to run custom script as showed on the image below: