Dealing with the "Call to undefined method" Error in OSMap

One of OSMap users faced the "Call to undefined method Joomla\CMS\Document\XmlDocument::addCustomTag()" error. You may see it trying to view either the "XML" or "Images" sitemaps.

The most likely reason for this error may be one of the 3-rd party system plugins you installed. In this blog post, I'll show you how to find which one of them is the source of the error.

Here is how this error looked on the frontend of the user's Joomla site:

call to undefined method

You start off by opening your Joomla administrator panel. Once in there, you want to go to "Extensions" > "Plugins":

go to extensions plugins

You will be taken to the administrative "Plugins" screen. On this screen, you want to click the "Search Tools" button:

click the search tools button

This will bring up the four filters. You want to click inside the "Select Type" filter:

click select type

This will display you a dropdown list of the types of plugins. In this list, you want to click "system":

set the filter to the system

Now would be a good time to start disabling your system plugins one by one. To disable a plugin, you want to click on the box next to the name of the plugin and check if the error disappeared:

disable plugins one by one

Keep disabling your 3-rd party system plugins until you find the one that causes the "Call to undefined method ..." error.

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About the author

Alex is a self-taught Microsoft Certified Professional based in England. He enjoys learning Joomla and helping beginners and web site administrators make the most of it.