I try to add points manually and send a message

I try to add points manually and send a message
" Failed to add reward points.
There are no errors in the log
How can I solve this problem? v3.9
Thanks

Are you sure you are using nopCommerce 3.90?
Have you done any customization or are you using an "Extended Reward Points" plugin?

New York wrote:
Yes, version 3.9
Extended "Reward Points" plugin has been installed and uninstalled.

The only place I see the message "Failed to add reward points" is in the language pack for nopC 4.20 and later.  Do you have any related error message in the System Log?
(After you try to add points manually and see the message, go to System Log.)

no, there are no messages in the system log. the error appeared in the form of a pop-up window in the admin panel.

In your admin Languages > String Resources , search for Value
  Failed to add reward points

What is the Resource Name?

New York wrote:

this value is missing

gnikitsin wrote:
what is the system name? do i need to add it? thanks

The system name comes from the plugin
For version 3.9 check the file Description.txt in the plugin directory

SystemName: Plugin.Name,
Version: X.XX,

What version is the plugin ?

@gnikitsin
I don't know why you are asking about "system name".  I'd like to determine how you could be seeing a message text that says "Failed to add reward points".   That text should be a string resource value for some Resource name.