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Undefined array key "cursor" #66
Description
This error was occurring on dialog this morning:
Error web.Error(#500: Undefined array key "cursor")
at web.frontend.Exceptions::handle() [line 105 of Frontend.class.php]
at web.frontend.Frontend::view() [line 138 of Frontend.class.php]
at web.filters.Invocation::proceed() [line 59 of BehindProxy.class.php]
at web.filters.Invocation::proceed() [line 41 of Filters.class.php]
at web.Filters::handle() [line 90 of Application.class.php]
at xp.web.srv.HttpProtocol::handleData() [line 64 of Kernel.class.php]
at peer.server.AsynchronousServer::{closure:peer\server\AsynchronousServer::select():74}() [...]
at peer.server.AsynchronousServer::service() [line 109 of Kernel.class.php]
at xp.web.srv.Standalone::serve() [line 81 of Runner.class.php]
at <main>::__error() [line 314 of Collection.class.php]
at com.mongodb.Collection::first() [line 136 of Repository.php]
at de.thekid.dialog.web.Home::index() [line 0 of StackTraceElement.class.php]
The relevant lines where this exception comes from:
$commands= Commands::reading($this->proto);
$result= $commands->send($options, $sections);
return new Cursor($commands, $options, $result['body']['cursor']);This means there is a body but it does not contain a cursor, which for the find or aggregate command issue cannot happen looking at the protocol; except maybe if it somehow became out of order; or if one of the cluster nodes points to something which replies with something "don't connect nere any longer" or something. Unfortunately, I couldn't reproduce this locally, and changing the server to use more verbose debugging is not possible without losing connections.
This protocol error should lead to the MongoDB client to disconnect, re-evaluate the cluster setup and subsequently reconnect. Restarting the Docker container did the trick, so I assume this would also work.
Activity
thekid commentedon Jul 10, 2026
Seems to happen in some case of weird cluster reorganization / reconnect scenario.
thekid commentedon Jul 12, 2026
Together with #67 and #68, this should now lead to a "packet out of order" protocol error and a subseqent re-connect. Queries will be retried.
thekid commentedon Jul 12, 2026
Integration testing started on https://dialog.friebes.info/, which has been upgraded to https://github.com/xp-forge/mongodb/releases/tag/v3.10.0