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== 4.76. I can't access one of my lists via the web interface. One of my lists is not sending mail. List locked. ==

Problems that affect only one list in an installation can be caused by stale locks for the list.

A list lock is implemented as a pair of files in mailman's locks/ directory. One file is named '<listname>.lock' and the other is named '<listname>.lock.<hostname>.<pid>.<seq>' where

<listname> is the name of the list<<BR>> <hostname> is the name of the host that set the lock<<BR>> <pid> is the process id of the process on <hostname> that set the lock<<BR>> <seq> is a sequence number

The contents of both files (actually they are the same file with two names - hard linked) is

/path/to/locks/<listname>.lock.<hostname>.<pid>.<seq>

There may be additional files named '<listname>.lock.<hostname>.<pid>.<seq>' for the same listname. These represent lock requests waiting for the lock to be relinquished.

Sometimes due to a crash of some sort, a lock will be left in place after the process that set it is gone. This is a stale lock. One can often identify a stale lock by its age. Also, if <pid> no longer exists on <hostname>, the lock is definitely stale.

Stale locks can safely be simply removed. If there are other processes waiting on the stale lock, removing the '<listname>.lock' file will allow the other processes to acquire and relinquish the lock normally.

See also [[../4.78 Troubleshooting- No mail going out to lists members|4.78 Troubleshooting- No mail going out to lists members]].

Note that pre-2.1.7 Mailman could stop sending to a single list because of a problem with a message in the lists/<listname>/digest.mbox file. This will not affect the web interface for the list, but if this is why the list is not sending, there will be a 'shunting' message and a traceback of an exception involving Mailman/Handlers/ToDigest.py in Mailman's 'error' log for each list post. See the post at [[http://mail.python.org/pipermail/mailman-users/2007-December/059426.html|http://mail.python.org/pipermail/mailman-users/2007-December/059426.html]] and other posts referenced by it for more information, but note that this post only discusses one specific error. There are many other possible message defects that can cause a different exception with the same end result.

Converted from the Mailman FAQ Wizard

This is one of many [[../Frequently Asked Questions|Frequently Asked Questions]].