Dovecot Crashes Upon Restart 
============================

.. contents::

How the Issue Manifests
-----------------------

Dovecot crashes and will not fully restart. 

Common Cause of the Issue
-------------------------

The internal memory settings for Dovecot are being reached when the service is active. 

Troubleshooting
---------------

Check the Dovecot Log for Memory Errors
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

#. Log in to the server at the CLI as root, either via SSH or from the terminal
#. With a text editor, open ``/var/log/dovecot/dovecot.log``. The following example uses the Vim text editor:

   .. code-block::

      vim /var/log/dovecot/dovecot.log

#. Search the log for output similar to the following--this indicates that the internal memory settings for Dovecot are 
   being reached and that is killing the service: 

   .. code-block::

      Oct 01 20:25:27 config: Fatal: block_alloc(67108864): Out of memory
      Oct 01 20:25:27 config: Error: Raw backtrace: /usr/lib64/dovecot/libdovecot.so.0(backtrace_append+0x42) [0x7f79ca718582] -> /usr/lib64/dovecot/libdovecot.so.0(backtrace_get+0x1e) [0x7f79ca71868e] -> /usr/lib64/dovecot/libdovecot.so.0(+0xe5b5e) [0x7f79ca722b5e] -> /usr/lib64/dovecot/libdovecot.so.0(+0xe5c01) [0x7f79ca722c01] -> /usr/lib64/dovecot/libdovecot.so.0(i_error+0) [0x7f79ca67ec96] -> /usr/lib64/dovecot/libdovecot.so.0(+0x1077d6) [0x7f79ca7447d6] -> /usr/lib64/dovecot/libdovecot.so.0(+0x10782b) [0x7f79ca74482b] -> /usr/lib64/dovecot/libdovecot.so.0(+0x7a8d3) [0x7f79ca6b78d3] -> /usr/lib64/dovecot/libdovecot.so.0(+0x7a879) [0x7f79ca6b7879] -> /usr/lib64/dovecot/libdovecot.so.0(settings_parser_init_list+0x13f) [0x7f79ca6b7b6f] -> /usr/lib64/dovecot/libdovecot.so.0(settings_parser_init+0x1a) [0x7f79ca6b7c1a] -> dovecot/config(+0x126e6) [0x560b0f1f06e6] -> dovecot/config(config_parser_apply_line+0x538) [0x560b0f1f1508] -> dovecot/config(config_parse_file+0x8e7) [0x560b0f1f2297] -> dovecot/config(main+0xba) [0x560b0f1ec30a] -> /lib64/libc.so.6(__libc_start_main+0xf5) [0x7f79ca291555] -> dovecot/config(+0xe39c) [0x560b0f1ec39c]
      Oct 01 20:25:27 master: Error: service(config): command startup failed, throttling for 60.000 secs
      Oct 01 20:25:27 config: Fatal: master: service(config): child 14958 returned error 83 (Out of memory (service config { vsz_limit=256 MB }, you may need to increase it) - set CORE_OUTOFMEM=1 environment to get core dump)
      Oct 01 20:25:27 stats: Fatal: Error reading configuration: read(/var/run/dovecot/config) failed: read(size=8192) failed: Connection reset by peer
      Oct 01 20:25:27 master: Error: service(stats): command startup failed, throttling for 60.000 secs
      Oct 01 20:25:27 master: Warning: Killed with signal 15 (by pid=13953 uid=0 code=kill)
      Oct 01 20:25:30 log(20795): Warning: Killed with signal 15 (by pid=1 uid=0 code=kill)

How to Resolve
--------------

#. Log in to the server at the CLI as root, either via SSH or from the terminal
#. At the CLI, navigate to ``/etc/dovecot/conf.d``
#. Using a text editor, create a new conf file named ``99-vsz_limit.conf``. The following example uses the Vim text editor:

   .. code-block::

      vim 99-vsz_limit.conf

#. Add the following to the file, replacing {256M} (which is the default setting) with the desired limit

   .. note::

      The most common practice when raising a setting like this is to double it. So, for example, as the default is ``256M``, the next setting to try
      would be ``512M``. This may require some trial and error to identify the correct setting. If the error still occurs after raising to ``512M``
      and restarting or reloading Dovecot, trying again with ``1024`` may be needed, etc. 

   .. code-block::

      default_vsz_limit = {256M}

#. Save the file, and exit the text editor
#. Restart or reload Dovecot

   .. code-block::

      systemctl restart dovecot 

   or

   .. code-block::

      systemctl reload dovecot