i remend

i remenber that i use elgg 2.3.3 thanks

Updates your Elgg version.

Elgg 1.12.16 is perfectly fine. It's still the supported LTS version. While the latest Elgg 2.3 version surely has advantages compared to Elgg 1.12 the image upload should work fine also on Elgg 1.12.

Image upload with Elgg's Files plugin or Tidypics or what?

Image upload might fail (beside uploading profile images) because image resizing might fail. Image resizing for larger image files requires a lot of memory. If you have set memory_limit in Elgg's .htaccess file too small it might be the cause of the failed image uploads.

Or you might need to increase post_max_size in .htacces for Elgg to be able to handle the image files (uploaded original file + resized image files).

You could test with an image file that works as profile image. If you can upload it also with the Files plugin (or Tidypics etc.) the problem is likely caused by the limits set in .htaccess and you would need to increase these limits. If the small image also fails when uploaded not as profile image you might have some buggy 3rd party plugin installed that breaks the image upload.

It depends on what you want to build.  I work with Elgg, Drupal, Ionic, and have dabbled in Laravel and (blech) Wordpress.  They're all different tools for different jobs.

The active development has certainly slowed down lately, I know I have been extremely busy with personal life and simply haven't had the time I used to put in.  That said, the latest version of Elgg is very good and I wouldn't hesitate to build something with it.  In fact I'm working on some high level projects for some very large companies using Elgg currently.  I wouldn't take the slowdown to mean it's not a useful or supported product.

Development might have slowed down but not stopped. And I don't think that it will stop in the foreseeable future. As there are only a few active developers the activity goes up and down depending on the available time of the devs. Just as it happens there has been quite a lot activity within the last few days.

Even with development stalling or stopping Elgg wouldn't get "obsolete" suddenly. It would still be possible to continue to use it - and all 3rd party plugins - as they would be at that time. And even then you (or other developers) could continue the development at any time because everything is open source.

Joompla, Drupal, Wordpress are CMS and therefore they have surely a different use than Elgg. Which system fits best depends on what you want to achieve. Can you get what you want with Elgg? Does it fits you needs? Or does any of the other systems fits your needs better. I would make a decision based on that - the presence - and not necessarily on what might or might not happen in the future.