Data too long for column 'payload' at row 1 when trying to set a profile photo / avatar using Snikket

[iii0s]

Environment

• ejabberd version: 26.03
• Erlang version: Erlang (SMP,ASYNC_THREADS) (BEAM) emulator version 12.3.2.15
• OS: Linux (Mageia)
• Installed from: official binary installer

Bug description

I have tried to set the profile image using Snikket, whicht never succeeded, so I did that using Monal IM. I have tried to check the logs in order to see, what is going on so I found the following:

2026-04-05 21:06:24.595181+02:00 [error] <0.550.0>@ejabberd_sql:check_error/2:1470 SQL query 'Q69783698' at {node_flat_sql,{851,9}} failed: <<"Data too long for column 'payload' at row 1">>
2026-04-05 21:06:24.602537+02:00 [error] <0.7256.0>@mod_pubsub:get_transaction_response/1:3967 Transaction aborted:
** exception throw: {aborted,<<"Data too long for column 'payload' at row 1">>}
in function ejabberd_sql:restart/1 (src/ejabberd_sql.erl:238)
in call from node_flat_sql:set_item/1 (src/node_flat_sql.erl:849)
in call from node_flat_sql:publish_item/7 (src/node_flat_sql.erl:272)
in call from mod_pubsub:node_call/4 (src/mod_pubsub.erl:3871)
in call from mod_pubsub:'-transaction/4-fun-0-'/3 (src/mod_pubsub.erl:3904)
in call from mod_pubsub:'-do_transaction/4-fun-0-'/3 (src/mod_pubsub.erl:3926)
in call from ejabberd_sql:execute_bloc/1 (src/ejabberd_sql.erl:690)
in call from ejabberd_sql:run_sql_cmd/4 (src/ejabberd_sql.erl:571)

I am not sure if this is related to the profile image or another thing, but after setting the profile image using Monal IM the error dissappeared.

If there is anything I can do to debug this, please tell me.

[licaon-kter]

Snikket iOS which is Siskin based

or

Snikket Android which is Conversations based?

[iii0s]

That is Snikket IOS. DB is MariaDB version: 11.4.10-MariaDB

[badlop]

I've setup MariaDB 12.2.2+maria~ubu2404 in a container, compiled ejabberd 26.03, and configured it to use mariadb for mod_pubsub.

Then I publish items like this:

<iq type='set' id='publish1'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='urn:xmpp:avatar:data'>
      <item id='111f4b3c50d7b0df729d299bc6f8e9ef9066971f'>
        <data xmlns='urn:xmpp:avatar:data'>/9j/4AAQSkZJRgABAQE ...  </data>
      </item>
    </publish>
  </pubsub>
</iq>

Depending on the data size, three things can happen in my case:

A) Connection gets closed because the XMPP stanza size exceeds max_stanza_size (262144 bytes in ejabberd example configuration)

<stream:error>
  <policy-violation xmlns='urn:ietf:params:xml:ns:xmpp-streams'/>
  <text xml:lang='en'
	xmlns='urn:ietf:params:xml:ns:xmpp-streams'>XML stanza is too big</text>
</stream:error>

B) PubSub stanza is rejected because payload size exceeds max_payload_size (250000 bytes in mod_pubsub source code)

<iq>
  ...
  <error type='modify'>
    <payload-too-big xmlns='http://jabber.org/protocol/pubsub#errors'/>
    <not-acceptable xmlns='urn:ietf:params:xml:ns:xmpp-stanzas'/>
  </error>
</iq>

C) Stanza is accepted, stored in the database, and published:

<iq xml:lang='es'
	to='admin@quinto/tka1'
	from='admin@quinto'
	type='result'
	id='publish1'>
  <pubsub xmlns='http://jabber.org/protocol/pubsub'>
    <publish node='urn:xmpp:avatar:data'>
      <item id='111f4b3c50d7b0df729d299bc6f8e9ef9066971f'/>
    </publish>
  </pubsub>
</iq>

---

In your case, you are triggering an unexpected result, let's call it case D)

Looking at the mysql.sql file, it says:

CREATE TABLE pubsub_item (
  nodeid bigint,
  itemid text NOT NULL,
  publisher text NOT NULL,
  creation varchar(32) NOT NULL,
  modification varchar(32) NOT NULL,
  payload mediumtext NOT NULL

That mediumtext is quite a big image:

MEDIUMTEXT |    16,777,215 (224−1) bytes = 16 MiB

I wonder what ejabberd configuration, what pubsub node configuration, and what stanzas are you using to trigger that problem. I also wonder if it makes sense to allow such big images to be used as avatars...