Hello,
as #alex told you, you have tried to modify the codes directly. one of them is creating the issue. we do not know in which file you have made changes. maybe you have not done it, it could be a third party plugin.
the only remaining solution is to deactivate all third-party plugins then manually update your theme.
refer:
https://wplms.io/support/knowledge-base/manually-updating-wplms/
if there is any default plugin in which you made changes then deactivate that plugin and install again.
it will resolve the issue.