Check out example codes for "mariadb unknown collation: 'utf8mb4_0900_ai_ci'". It will help you in understanding the concepts better.

Code Example 1

I just opened the dump.sql file in Notepad++ and 
hit CTRL+H to find and replace the string 
"utf8mb4_0900_ai_ci" and replace with "utf8mb4_general_ci"

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