updating from J3.10 to J4.4.1 causes a lot of errors and doesnot work

Again, thanks. However, as Helix 3 is an old framework, what is the best substitute according to you? I other words, is there a template similar to helix3, as much as compatible with it so i can run it with no or minimum changes;
I understood that helix ultimate is only a template, not a framework. I did not try it. Maybe is it a good replacement for helix3. Right or stupid idea?
regards.
jluc

Hi
thanks for your help solving previous issues
finally i succeed upgrading my site from J310 to J441.
It is now J441, Helix3 305, SPPB 523 icAgenda 3824 PHP 8126
Every thing rises up however i get a warning i don't succeed solving.
) Warning: Undefined property: stdClass::$content in D:\wamp364\www\bpp\administrator\components\com_sppagebuilder\editor\helpers\ApplicationHelper.php on line 89
anybody to help?
Thanks
jluc

Paul, thanks for yor reply,

1. it is raw helix3 template.
2. Casiopea gives the same warning message.
3. Both editors Tiny MCE and JCE have been tested. JCE release 2 9 55. The same warning message happens with both editors.
4. Regarding pages that present the problem: not all pages present the problem. Pages wich make a simple link to an external website do not have the warning message

I got back to sppb 3810 : the warning message is not there, but another error message comes as soon as i try to access page for editing. Unfortunately i lost the error message, when my previous session expired. It does not matter, because then i got back to sppb 524 as i saw this version could match the installation. I got some sppb 524 installed but install ended with error message Call to a member function children() on null.
I tried to deinstall everything sppb. Got the rrror Call to a member function children() on null.. Some elements still present after desinstall. I reinstalled sppb 523 and got the same error message Call to a member function children() on null.. However release 523 seems to be there. Maybe partially. in the frontend still the warning message. In the backend i tried to edit somme sp pages. And i got an error message : error status code 500. In fact i can't access no sp pages for editing.
So, to resume:
SPPB release 523 installed 3 elements and ended with error Call to a member function children() on null. Elements installed are:
1.Menu admin SP Page Builder SP Page Builder Administration Module 1.4 01-08-2014
2.SP Page Builder Administration Composant 5.2.3 01-09-2014
3.SP Page Builder (fr-FR) Site Fichier 1.0 13-04-2017
Frontend has the warning message.
Backend doesnt allow to edit any sp pages: error code 500 as soon as i try to access pages.

hello
i made an export from a faulty sppb page. In fact all pages have the same problem. The one that do not present the problem are not sp pages. I was wrong.
The export is a json file. I made two exports (2 different pages). I can attach also a word file with screen shot of what i see on my screen when i display or edit or try to modify pages.
The question is how can i share this.
here is a link on a google drive. Please let me know if it reachable:
https://drive.google.com/file/d/1-j2-ODvpaaDvJ8NnlYjLXd77WaDDNM3z/view?usp=drive_link
regards
jluc

hello paul,
Finally i uninstalled every SP Page Builder from joomla. I tried using admin extension uninstall. But it did not uninstall all. I got some errors. I have to do manual uninstall, delete each directory "sp page builder" given by uninstall process from admin dashboard, and then delete sp page builder from database. I made a new installation from SP Pagebuilder 5.2.4 pro. Now every went ok. Probably some thing went wrond when uninstalling and then installing new or old version. I suppose uninstall process not working as expected, or maybe i did not follow what uninstall process told me ???. And the sp pb datage went corrupted. uninstalling manually solved the problem.
Please, i don't know how to indicate the problem and issue are solved. Can i let you do? By the way thanks a lot for your help.
regards
jluc