This is caused by the JMango360 Plugin versions: 4.0.0, 4.0.1, 4.0.2, 4.0.3. These versions don't work with the custom theme settled in Default scope in the Magento backend.
Please choose one of two solutions listed as below in order to get this issue solved:
1. Option 1: Upgrade the plugin to the newer version (4.0.4 and forward), please go to JMango360 Back Office and download package file of plugin to upgrade the latest plugin.
2. Option 2: In case you don't want to upgrade the plugin:
- Please go to Mangento Backend >> System >> Configuration >> Design
- Hereby, remove your custom theme created in Skin (CSS Image) of "Default Scope"
Please contact us via this link if it doesn't work after all.
To download the package file of Magento plugin, you please:
- go to JMango360 Back Office
- In Settings >> Magento Integration Settings >>Click to view how to integrate with your Magento store.