Hi Andreas,
Is this a database that has only ever been used with 3.10.0 or was the
data loaded with a previous version at some time in the past?
The problem occurs silently during loading. There is no sign of the
problem at the time and the system works just fine while the RDF term,
or terms, are also in the node table cache.
Then the system is restarted.
Then the RDF term is needed for a query and the errors are reported.
But the problem originated back when the data was loaded or updated, may
be several restarts ago.
Of course, it may be a different issue in which case, but the error
message is consistent with the known bug.
Have you been backing up the server on a regular basis? A backup is
NQuads so it is pulling every RDF term from disk (subject to already
being cached).
Andy
On 07/03/2019 20:47, Walker, Andreas wrote:
Hi Andy,
I am running Version 3.10.0. The problem with reloading the database is the
regular (multiple times a day) recurrence of the problem, so if there are any
strategies to avoid it, I'd appreciate any advice.
Best,
Andreas
________________________________
Von: Andy Seaborne <a...@apache.org>
Gesendet: Donnerstag, 7. März 2019 21:12
An: users@jena.apache.org
Betreff: Re: AW: Error 500: No conversion to a Node: <RDF_Term >
Hi Andreas - which version are you running?
It does not look like the corruption problem, which is now fixed.
The best thing to do is reload the database again. Whatever terms were
messed up are permanently damaged I'm afraid.
Andy
On 07/03/2019 10:49, Walker, Andreas wrote:
Dear all,
as a quick follow-up which might be helpful in identifying the error; I can
currently run a SPARQL query (just listing any triples) with LIMIT 80, but no
higher, before I run into the error, so it seems like there might indeed be a
particular part of the database that is corrupted.
Best,
Andreas
________________________________
Von: Walker, Andreas <andreas.wal...@sub.uni-goettingen.de>
Gesendet: Mittwoch, 6. März 2019 10:42:32
An: users@jena.apache.org
Betreff: Error 500: No conversion to a Node: <RDF_Term >
Dear all,
from time to time, my Fuseki server starts throwing the following error message
on any SPARQL query I pose to one of my graphs:
"Error 500: No conversion to a Node: <RDF_Term >"
Unfortunately, I couldn't find any explanation of this error message, beyond a
discussion of a corrupted TDB2 database.
(https://users.jena.apache.narkive.com/LF4XE801/corrupted-tdb2-database)<https://users.jena.apache.narkive.com/LF4XE801/corrupted-tdb2-database>
Once this happens, the only thing I could do so far is to drop the entire
afflicted graph and rebuild it, but of course that isn't going to be a viable
solution in the long term.
The only way I interact with Fuseki is by starting and stopping it, querying it
via the SPARQL endpoint (and sometimes through the web interface, e.g. when
troubleshooting my application), and uploading new triples (as turtle files)
via the web interface. I haven't been able to find a pattern in when the error
appears so far.
Any insights into why this error appears, and what to do in order to avoid it?
I'd appreciate any help.
Best,
Andreas
