When uploading a plugin in .zip format, you need to be sure that your server will allow the upload for the file size of the plugin. To see what is the Maximum File Size for your server, check the Server Information page on your MainWP Dashboard site.
If PHP Function tmpfile() is disabled on the server where the Dashboard is hosted, the upload of plugins will fail. Please contact your hosting provider and have them enable the function for you.
However, the most likely reason would be a security rule preventing the connection to the server where the Dashboard is hosted.
Please try to:
- Remove any security rules present in the .htaccess file where the MainWP Dashboard is installed
- Disable any security plugins running on WordPress where the MainWP Dashboard is installed
- Disable security measures, such as firewall, of the Hosting provider where the MainWP Dashboard is hosted
- Disable HTTP Basic Auth protection on the URL of the MainWP Dashboard
Please note that if the MainWP Dashboard is hosted locally, the localhost will most likely not be configured to accept external traffic, and the same error message “Upload failed.” will be displayed.
Server self connect
To check for potential issues, go to MainWP Dashboard > Info > Server and locate the Server self connect field.
If the value is anything other than “Response Test O.K.”, it may be a good idea to contact the hosting provider’s Support and have them verify why the loopback connection is failing.