From the ARRL:
The past few weeks have been a frustrating time for many users of the
ARRL’s Logbook of The World (LoTW) QSO confirmation system. The
problems began with a 3-1/2 day outage during the first week of
November — a particularly busy time of the year for log uploads. When
the system was brought back on line, a large queue of logs awaiting
processing developed and processing times lengthened well past normal
Another, much more subtle problem cropped up at about the same time:
some logs began disappearing from the queue, apparently at random.
Users had been advised at the time the log was uploaded that it was
“queued for processing,” and so they were understandably upset when
the log was not processed, even after the several-day delay that most
logs were experiencing.
Because of its random nature, it took the ARRL IT staff a while to
figure out what was happening. When LoTW was designed more than a
decade ago — long before the present IT staff was here — an
assumption was made as to how many logs could possibly be in the queue
at a given time. The assumption was based on users uploading their
most recent QSOs perhaps once a week or once a month. The environment
in which LoTW now operates is quite different from that assumption, in
that many users now upload logs with small numbers of QSOs in them,
almost in real time. This creates a much larger number of separate
When a log is uploaded, it is identified by a file name that is
assigned by the user. Because there is no way to avoid duplication of
file names that are assigned in this fashion, the LoTW system renames
each file. Because of the unusual processing delay — combined with
the dramatic increase in the number of submitted logs — the system
began to run out of unique identifiers for the log files. This
resulted in a file sometimes being renamed with an identifier that had
already been assigned to a log that was still in the queue, causing
the earlier log to be overwritten.
Once the problem was identified, designing a fix was relatively easy.
It should be in place by 2359 UTC November 28. Because the number of
overwritten logs is relatively small, we have decided to keep the
system available for use, even though this may result in a few more
logs being lost until the fix is in place.
We apologize for the inconvenience that users have experienced, and
especially for being unable to explain what was happening until now.
We want to emphasize that no data from processed logs has been lost.
That data is secure and backed up. If you have had a log disappear
after it was “queued for processing,” the solution is to upload the
log file again, preferably after the bug fix is in place. We will
announce when that occurs.
David Sumner, K1ZZ
Chief Executive Officer, ARRL
November 28, 2012