A technical problem with the server created an error. Try again to continue what you were doing.

[AbhinavKSaxena]

Well , The newer version of Magento 2.3 has this issue of not 
A technical problem with the server created an error. Try again to continue what you were doing. If the problem persists, try again later.
It has a general fix which is to add changes in vendor file (which isn't a good practice).
We need to add changes to the following files
vendor/magento/module-theme/view/adminhtml/ui_component/design_config_form.xml

We need to add two changes :-

• Change "fileUploader" to "imageUploader" in the "formElement" attribute on line 57, 154
• We will then need to flush the cache and the logo icon upload issue would fix

[paramjot_jassal]

Thank you this has fixed the problem for me in the header upload and the html head upload. I still have the same problem in the 'Transactional email' section at the bottom of the same section.

I am assuming there is another file that needs the same fix?

---

@AbhinavKSaxena wrote:

Well , The newer version of Magento 2.3 has this issue of not 
A technical problem with the server created an error. Try again to continue what you were doing. If the problem persists, try again later.
It has a general fix which is to add changes in vendor file (which isn't a good practice).
We need to add changes to the following files
vendor/magento/module-theme/view/adminhtml/ui_component/design_config_form.xml

We need to add two changes :-

• Change "fileUploader" to "imageUploader" in the "formElement" attribute on line 57, 154
• We will then need to flush the cache and the logo icon upload issue would fix

---

[william_bowling]

This was perfect and did the trick. Thanks for the help.

[john_dante]

In vendor/magento/module-theme/view/adminhtml/ui_component/design_config_form.xml file change fileUploader to imageUploader on line number 57 and 154

i try to this but still same problem is showing. what to do ?

[zjaffery]

edit only line 154

[tom_granroth]

I found this solution:

https://github.com/chaplynsky/magento2/commit/ba325135318e2c856e5300d7139f529662679d3e

[dan_silver]

worked for me, Magento 2.3

[bhathiya_kariya]

I got the same problem. But I solved it myself. To prevent that error first you need to change  change fileUploader to imageUploader on line number 57 and 154 in design_config_form.xml file which in vendor\magento\module-theme\view\adminhtml\ui_component path. Then refresh the browser and go to Admin panel > System > Cache management > select all > click submit. After doing that refresh your browser again. Now go to your store configuration location and you can upload images what you want without any error. I hope this will works on you. Good Luck!

[unicod3]

I am also having the same issue,

I did what AbhinavKSaxena told, it works on logo settings page, but when i go to other pages like catalog > products, I still get the same error pop-up 

[Griehle]

Same issue after upgrade to 2.3