That's most common because your theme is really outdated, please update it first.
Here is an instruction on how to update the theme: http://themes.muffingroup.com/betheme/documentation/#general Theme updates will not delete your content unless you have changed the files directly in which case we suggest using a child theme. We also recommend creating a backup file. Please remove the theme completely from your theme folder and install a fresh copy. Do not overwrite files.
Comments
Here is an instruction on how to update the theme:
http://themes.muffingroup.com/betheme/documentation/#general
Theme updates will not delete your content unless you have changed the
files directly in which case we suggest using a child theme.
We also recommend creating a backup file.
Please remove the theme completely from your theme folder and install a
fresh copy. Do not overwrite files.