Everytime I tried to install themes and modules in my backdrop site, I get this error.But where I can set up the premissions? I'm using a Admin Account with the premisson to install themes and modules.
The problem might be with your server permissions.
1) I recommend taking a look at this thread and seeing if anything here is helpful to you.
That thread will point you at this resource:
2) Provide additional information about your hosting.
* Where are you hosting?
* Do you have access to the server level permissions?
* Are they configured as described in the file-permissions-and-ownership article?
I find that most "permissions" related problems are related to ownership and permissions of files and directories on the server.
There is an existing issue in the Backdrop CMS core issue queue to improve this error message to be more helpful. We would welcome additional input and suggestions. We've updated that issue to reference this situation.
NOTE: The more people that comment on issues in the core issue queue, the more attention those issues get. Help make Backdrop better by sharing your own experiences and ideas both here and in the github issue queue (whichever works better for you).