I updated one of our secondary websites (not very active) and got an error on backend :

Error displaying the error page: Call to undefined method JAdminCssMenu::addChild(): Call to undefined method JAdminCssMenu::addChild()

I've not seen any errors so far with all my local test sites but I believe that error that you are getting is most likely coming from a Joomla template. What template do you use?

I've not seen any errors so far with all my local test sites but I believe that error that you are getting is most likely coming from a Joomla template. What template do you use?

I am using the admin default joomla template, on front end all working great, i am using ED only on this website.
the problem is in the backend, the admin menu is visibile but cannot open any menu.

Just tested my local instance and it all works fine with 3.8. Do you have any 3rd party modules or plugins instaled?

Hmmm dont remember, i add the login in the first post if want to see directly

This is definitely not EasyDiscuss. Just searched through the entire codebase and none of the code JAdminCssMenu is found in EasyDiscuss.

Who said its from ED
Maybe the update was not complete! is there a way to re-update ?
i cant access the update from back end if there is another way to do it.

Hm, I am not sure to be honest.

Anyway since this is not related to our products or support related to the products, I will be moving this to the appropriate chatzone category

If i find a solution i'll post it here

From the code forensics, I found out that only the mod_menu in Joomla's admin folder uses JAdminCssMenu. You might want to check if the file /administrator/modules/mod_menu/helper.php exists on the site.

Thnaks Mark, i tried to reupload this folder files (helper) and seems not work.
I'll post this issue on the joomla.org website.

I am using the admin default joomla template, on front end all working great, i am using ED only on this website.
the problem is in the backend, the admin menu is visibile but cannot open any menu.

I had a similar issue on another component menu not working after a 3.8 update. The database for the menus was corrupted on some components. The access level was set incorrectly for each component menu item. Database table "menu" access level was not set to 1. Changed the access level to 1 for the menu items and then the menus worked.

Hi Bruce, thanks for you input here !

Can you tell me please how to resolve that please ? If possible with screenshots

From the looks on the Joomla issue tracker, it seems like there is a bug related to the menu. I am not too sure if this is related but feel free to check their codes here, https://github.com/joomla/joomla-cms/milestone/26?closed=1

If you have CPanel and are somewhat familiar with phpMyAdmin, then proceed with my instructions. Please make a backup of your site using Akeeba backup first. A couple wrong clicks in the database and you could trash your site. This fix will only work if the incorrect menu access number is in the database. When you look at the menu table for EasyBlog, they all should be "1" or maybe a couple of "0s" for access level. They should not be anything else. If you have "5s" for access rights, then this most likely will fix your problem. Instructions are in the screenshots. I made the instruction for manually changing each menu item one at a time as this is safer if you are not comfortable with SQL queries. Not sure of your skill level, so I made the instructions based on the fact you do no alter databases with queries. If you do, you could simply search for access in "menu_type" for any access that are set at 5 and change to 1.

Hello Bruce, i checked all menus and seems to be correct (0,1),
The probleme was caused by JA Builder, how to resolve it :

https://www.joomshaper.com/forums/joomla-3-8#reply-100128

Hello Bruce, i checked all menus and seems to be correct (0,1),
The probleme was caused by JA Builder, how to resolve it :

https://www.joomshaper.com/forums/joomla-3-8#reply-100128

Thats SP Pagebuilder not JA Builder. I see a lot of this problem and its bcs of SP Pagebuilder version 2.5.1 if you have updated to version SP Pagebuildr 2.5.3 before you update to Joomla 3.8 you wouldnt have that problem.

https://www.joomshaper.com/blog/how-to-get-ready-for-joomla-3-8

sorry yes sp builder

Thanks for letting me know about that. We are not using SP Pagebuilder but a client might, so again thanks for the heads up.