Date: 2015-10-28 18:38:59 +0100
From: John Thomas <>
To: clients devs <>
Version: 11.21.5 (Jul2015)

Last updated: 2016-01-15 11:38:10 +0100

Comment 21417

Date: 2015-10-28 18:38:59 +0100
From: John Thomas <>

User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_10_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/46.0.2490.80 Safari/537.36
Build Identifier:

Every once in a while, attempting a query through mclient will fail with the response "Challenge string is not valid". Simple workaround is to just retry. In my testing, it is happening once every thousand attempts on average.

Reproducible: Sometimes

Steps to Reproduce:

1. In ruby: (1..10000).each { |i| result = echo "select 1;" | mclient my_db; puts result unless $?.success? }

Actual Results:

Running this just now, I got 12 lines of "Challenge string is not valid".

Expected Results:

No failures

This was noticed connecting through mclient, but I would assume the failure case is actually caused by either the mapi library or mserver itself.

Comment 21585

Date: 2015-11-24 17:42:37 +0100
From: MonetDB Mercurial Repository <>

Changeset 1c398dba145e made by Sjoerd Mullender sjoerd@acm.org in the MonetDB repo, refers to this bug.

For complete details, see http//devmonetdborg/hg/MonetDB?cmd=changeset;node=1c398dba145e

Changeset description:

Only connect once when getting redirected from merovingian.
This hopefully fixes bug #3841.

Comment 21630

Date: 2015-12-02 16:17:25 +0100
From: @sjoerdmullender

Closing, since I can't reproduce the problem anymore.

Comment 21631

Date: 2015-12-02 16:18:18 +0100
From: John Thomas <>

Thanks for the fix.