"The database connection failed. Please check your database configuration in include/db/config.php. If the configuration is okay, check if the database server is running."
I've gotten that one as well as some variation of this:
Phorum Database Error
Sorry, a Phorum database error occurred. Please try again later!
Error:
Lost connection to MySQL server during query (2013): SELECT * FROM phorum_messages WHERE forum_id = 2 AND thread = 1550232 AND status =2 ORDER BY message_id
Backtrace:
Function phorum_database_error called at {path to Phorum}/include/db/mysql/mysqli.php:212 ----
Function phorum_db_interact called at {path to Phorum}/include/db/mysql.php:1433 ----
Function phorum_db_get_messages called at {path to Phorum}/read.php:363 ----