Version 4.0.1 is available, it fixes the following bugs:

• force key "return" to command "/input return" when migrating legacy keys
• display actual key name and command with Alt+k, remove key Alt+K (grab raw key) and associated commands /input grab_raw_key and /input grab_raw_key_command
• check for newline characters in string_is_whitespace_char
• do not convert option name to lower case in API functions config_set_plugin and config_set_desc_plugin
• fix crash on quit with Guile < 3
• reply to a IRC CTCP request sent to self nick
• sent "QUIT" message to IRC servers connected with TLS on /upgrade