Can't update plugins

When I chek for new plugins and try to update them all, FRD try to update each one at a time and displays the folowing message after each pluging on the list during the process: "ERROR: Access is denied".
At the end, it finally says: "Update failed. Nothing was updated"

I can still download from some servers, but some of them not, because I can't update the required plugin.

What may be causing this?

Thanks in advance

[wordrider.net]

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