Error in Logs for Subscribe by Email

I'm seeing this error in the logs. We have been experiencing some database issues and I'm trying to triage them. I'm hoping you might be able to shed some light on what might be causing this issue:

[22-Jan-2016 16:34:55 UTC] WordPress database error Deadlock found when trying to get lock; try restarting transaction for query DELETE FROMwp_1795_optionsWHEREoption_name` = '_transient_sbe_pending_mails_sent' made by include('wp-load.php'), require_once('wp-config.php'), require_once('wp-settings.php'), do_action('init'), call_user_func_array, Incsub_Subscribe_By_Email->init_plugin, Incsub_Subscribe_By_Email->maybe_send_pending_emails, get_transient, delete_option

I'm on a WP Multisite, running 4.4.1. The plugin is activated on a site by site basis (not network enabled).

  • Adam Czajczyk
    • Support Gorilla

    Hello @mrjarbenne,

    I hope you're well today and thank you for your question!

    This error can be caused by a number of issues but most often is a result of:
    - some kind of cache conflict
    - a plugin that's flushing rewrite rules in a wrong way

    Please try clearing your site's cache and disabling cache entirely (if you're using any cache plugin such as e.g. W3 Total Cache) and see if it helps.

    If it doesn't, please run a full theme/plugin conflict test by following a flow chart from this article:

    https://premium.wpmudev.org/manuals/using-wpmu-dev/getting-support/

    The "one plugin to leave enabled" should be Subscribe by Email. This should let you identify the main culprit and I'll investigate it further.

    Let me know the result, please!

    Best regards,
    Adam

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