Breaking Stuff with Multiple Errors

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Plugins and Theme troubleshooting points at Appointments+ causing errors.

I did notice a mispelling (below) but I don't know where to correct this.
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Warning: call_user_func_array() expects parameter 1 to be a valid callback, class 'Appointments' does not have a method 'post_ceontent' in /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php on line 235

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 977

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 978

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 979

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 980

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 981

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 982

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 985

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 986

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 987

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 988

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 991

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 992

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 993

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 994

Warning: Cannot modify header information - headers already sent by (output started at /var/sites/a/asoldier.net/public_html/wp-includes/plugin.php:235) in /var/sites/a/asoldier.net/public_html/wp-includes/pluggable.php on line 1228