Your jumla theme seems to be the error.
how to solve this problem?
That’s best asked of the theme’s developers at https://www.ads-software.com/support/theme/jumla/
If you need immediate access to dashboard, switch to the unedited default Theme (Twenty Twenty, etc.).
If you don’t have access to your Dashboard’s Appearance page, access your server via SFTP or FTP, or a file manager in your hosting account’s control panel (consult your hosting provider’s documentation for specifics on these), navigate to /wp-content/themes/ and rename the directory of your currently active theme. Alternately, you can remove other themes except the default theme (Twenty Twenty, etc.). That will force your site to use it.
