First option:
- Settings → System → Updates
- Press the ‘check for Updates’ button top right
- Press the
...top right, and ensure skip updates is not ticked
Link to Updates – My Home Assistant
Second option:
- Install the Terminal & SSH Add-On
- Select Terminal from the web interface to get a HASS command line shell
- Try:
ha refresh-updates - Try:
ha available-updates - Try:
ha core update - Try:
ha core info
PS Text formatted with code blocks is much easier to read and understand if you want to post error messages. Right-Shift-Click selects text and copies it from the web terminal.
If this helps, 
this post!