Try deactivating all plugins.If that resolves the issue, reactivate each one individually until you find the cause.
If that does not resolve the issue, try switching back to your old theme for your version of WordPress to rule-out a theme-specific issue.
If you weren’t able to resolve the issue by either resetting your plugins and theme, we may be able to help, but we’ll need a more detailed error message and your site url too here.
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