Dovecot Fatal: master: service(imap): child 102561 killed with signal 6 (core dumped)

I have a postfix mail server that works perfectly, but when I try to connect it with Thunderbird it gives me this error

Fatal: master: service(imap): child 102561 killed with signal 6 (core dumped)

Here are the configuration files

main.cf

# See /usr/share/postfix/main.cf.dist for a commented, more complete version


# Debian specific:  Specifying a file name will cause the first
# line of that file to be used as the name.  The Debian default
# is /etc/mailname.
#myorigin = /etc/mailname

smtpd_banner = $myhostname ESMTP $mail_name (Ubuntu)
biff = no

# appending .domain is the MUA's job.
append_dot_mydomain = no

# Uncomment the next line to generate "delayed mail" warnings
#delay_warning_time = 4h

readme_directory = no

# See http://www.postfix.org/COMPATIBILITY_README.html -- default to 2 on
# fresh installs.
compatibility_level = 2



# TLS parameters
smtpd_use_tls = yes
smtpd_tls_cert_file=/etc/letsencrypt/live/mail.mastad.pl/fullchain.pem
smtpd_tls_key_file=/etc/letsencrypt/live/mail.mastad.pl/privkey.pem
smtpd_tls_security_level=may

smtp_tls_CApath=/etc/letsencrypt/live/mail.mastad.pl/
smtp_tls_security_level=may
smtp_tls_session_cache_database = btree:${data_directory}/smtp_scache


smtpd_relay_restrictions = permit_mynetworks permit_sasl_authenticated defer_unauth_destination
myhostname = mastad
mydomain = mastad.pl
mail_spool_directory = /media/mail
alias_maps = hash:/etc/aliases
alias_database = hash:/etc/aliases
myorigin = /etc/mailname
mydestination = $myhostname localhost.$mydomain localhost $mydomain
relayhost = 
mynetworks = 127.0.0.0/12 172.31.1.1
mailbox_size_limit = 0
recipient_delimiter = +
inet_interfaces = all
inet_protocols = all
home-mailbox = /media/mail
smtpd_sasl_type = dovecot
smtpd_sasl_path = private/auth
smtpd_sasl_local-domain = 
smtpd_sasl_security-options = noanonymous,noplaintext
smtpd_sasl_tls-security-options = noanonymous
broken_sasl_auth_clients = yes
smtpd_sasl_auth_enable = yes
smtp_tls_note_starttls_offer = yes

smtpd_tls_loglevel = 1
smtpd_tls_received_header = yes
smtpd_tls_mandatory_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1 TLSv1.2
smtpd_tls_protocols = !SSLv2, !SSLv3, !TLSv1, !TLSv1.1, TLSv1.2

virtual_mailbox_domains = mail.mastad.pl

10-ssl.conf:

##
## SSL settings
##

# SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>
ssl = yes

# PEM encoded X.509 SSL/TLS certificate and private key. They're opened before
# dropping root privileges, so keep the key file unreadable by anyone but
# root. Included doc/mkcert.sh can be used to easily generate self-signed
# certificate, just make sure to update the domains in dovecot-openssl.cnf
ssl_cert = </etc/letsencrypt/live/mail.mastad.pl/fullchain.pem
ssl_key = </etc/letsencrypt/live/mail.mastad.pl/privkey.pem

ssl_cipher_list = ALL:!LOW:!SSLv2:!EXP:!aNULL

# If key file is password protected, give the password here. Alternatively
# give it when starting dovecot with -p parameter. Since this file is often
# world-readable, you may want to place this setting instead to a different
# root owned 0600 file by using ssl_key_password = <path.
#ssl_key_password =

# PEM encoded trusted certificate authority. Set this only if you intend to use
# ssl_verify_client_cert=yes. The file should contain the CA certificate(s)
# followed by the matching CRL(s). (e.g. ssl_ca = </etc/ssl/certs/ca.pem)
#ssl_ca = 

# Require that CRL check succeeds for client certificates.
#ssl_require_crl = yes

# Directory and/or file for trusted SSL CA certificates. These are used only
# when Dovecot needs to act as an SSL client (e.g. imapc backend or
# submission service). The directory is usually /etc/ssl/certs in
# Debian-based systems and the file is /etc/pki/tls/cert.pem in
# RedHat-based systems.
ssl_client_ca_dir = /etc/letsencrypt/live/mail.mastad.pl/
#ssl_client_ca_file =

# Require valid cert when connecting to a remote server
#ssl_client_require_valid_cert = yes

# Request client to send a certificate. If you also want to require it, set
# auth_ssl_require_client_cert=yes in auth section.
#ssl_verify_client_cert = no

# Which field from certificate to use for username. commonName and
# x500UniqueIdentifier are the usual choices. You'll also need to set
# auth_ssl_username_from_cert=yes.
#ssl_cert_username_field = commonName

# SSL DH parameters
# Generate new params with `openssl dhparam -out /etc/dovecot/dh.pem 4096`
# Or migrate from old ssl-parameters.dat file with the command dovecot
# gives on startup when ssl_dh is unset.
ssl_dh = </usr/share/dovecot/dh.pem

# Minimum SSL protocol version to use. Potentially recognized values are SSLv3,
# TLSv1, TLSv1.1, and TLSv1.2, depending on the OpenSSL version used.
#ssl_min_protocol = TLSv1

# SSL ciphers to use, the default is:
#ssl_cipher_list = ALL:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH
# To disable non-EC DH, use:
#ssl_cipher_list = ALL:!DH:!kRSA:!SRP:!kDHd:!DSS:!aNULL:!eNULL:!EXPORT:!DES:!3DES:!MD5:!PSK:!RC4:!ADH:!LOW@STRENGTH

# Colon separated list of elliptic curves to use. Empty value (the default)
# means use the defaults from the SSL library. P-521:P-384:P-256 would be an
# example of a valid value.
#ssl_curve_list =

# Prefer the server's order of ciphers over client's.
#ssl_prefer_server_ciphers = no

# SSL crypto device to use, for valid values run "openssl engine"
#ssl_crypto_device =

# SSL extra options. Currently supported options are:
#   compression - Enable compression.
#   no_ticket - Disable SSL session tickets.
#ssl_options =