Cannot Edit Pages

Hello,

I cannot edit pages anymore.
Visual composer is perpetually loading and I get this error from the console:

Uncaught SyntaxError: Unexpected token < in JSON at position 24289
at JSON.parse (<anonymous>)
at Object.renderLegacySettingsComplete (fl-builder-ui-settings-forms.js?ver=2.2.1.5:421)
at Object.<anonymous> (fl-builder-ui-settings-forms.js?ver=2.2.1.5:403)
at Object.success (fl-builder.js?ver=2.2.1.5:9291)
at i (jquery.js?ver=1.12.4-wp:2)
at Object.fireWith [as resolveWith] (jquery.js?ver=1.12.4-wp:2)
at x (jquery.js?ver=1.12.4-wp:4)
at XMLHttpRequest.c (jquery.js?ver=1.12.4-wp:4)

Can you please help?
I’ve already deactived all the other plugin, but it hasn’t worked.

Patrizia