I just moved a wordpress multisite website with New Blog Template plugin to a hosting enviroment that uses PHP5 and I was getting an error. The tech at the hosting provider says it was old code with the plugin that is not compatible with php5.
He said he corrected the code, will you please ask the developer to look at the new code and see if it is correct?
It appears all issues with this environment have been taken care of.
Line 1217 of the following file had an error: /var/www/vhosts/mywebsite.com/wp-content/plugins/blogtemplates/blogtemplatesfiles/blog_templates.php
It appears that it was because of older code not compatible with PHP5. While we don't support your code (Or in this case, someone elses code that you are using) this was a fast fix:
OLD: $this->options['templates'][ $key ] = array_merge( $this->options['templates'][ $key ], $options );
NEW: $this->options['templates'][ $key ] = array_merge( $this->options['templates'][ $key ], (array)$options );