Error Servidor Dedicado 1 and 1 | Develop Site

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Cuando agregamos un nuevo plugin en windows server 8 de 1 and 1 aparece el siguiente error

Warning: DOMDocument::save(....\vhosts\domain.com\httpdocs/sitemap.xml) [domdocument.save]: failed to open stream: Permission denied in .....\vhosts\domain.com\httpdocs\wp-content\plugins\google-sitemap-plugin\google-sitemap-plugin.php on line 162

Undefined
Taxonomy upgrade extras [pt-pt:field:taxonomyextra:forum:label]: