Contact form 7 show php error in the user and sometimes take too long to load

Hi, my name is ibad, i have a problem with my plugin, contact form 7. There’s an error when the user try to upload a file. When i check in the messages menu for cf7 on wp admin that’s alert shown because php error. What should i do? Any suggestions?

Also in some cases the cf7 loading too long, even in fast internet connection. What’s wrong with the plugin?

Btw i’ve added materials design plugin for my cf7

Thank you in advance,
Ibad

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