Unhandled rejection Error: Error parsing url: change this

My version of HedgeDoc is: 1.7.2

I’ve executed the “NODE_ENV=production yarn start” command and shown “UnHandled Rejection Error: Error parsing URL: change this”

I cleared out all the “change this” in config.json

Did you just clear the “change this” values from your config.json or did you also remove the config keys you didn’t need? The config should only contain the properties that you want to configure.

Also make sure to change the .sequelizerc file to match your database config.

Thank you very much for your help,I just clear the “change this” values
I changed the.sequelizerc and cleared the “url” value
I use MySQL database

but when I excute “NODE_ENV=production yarn start” an error occurred again
This error is
"ERROR: Dialect needs to be explicitly supplied as of v4.0.0
error Command failed with exit code 1.

This is my .sequelizerc file

I probably expressed myself not clear enough.

I see, you cleared the facebook id and secret values. So you probably don’t want to use facebook as an authentication provider.
In this case just delete the entire lines for this. So you would remove these lines at least:

"facebook": {
  "clientID": "",
  "clientSecret": ""

Next, you said that you cleared the url in .sequelizerc. You shouldn’t do this. This file is used at startup by the sequelize-cli-tool which prepares your database for usage with HedgeDoc.
Just fill in the url with the same values as your database config. It should be something like this:

Thank you very much,Your expression is very clear, sorry, I am a Chinese, my English is not good, I can only rely on the interpreter to communicate with you, should I set the URL like this?

Somethig along those lines should do the trick.

I have changed the value of ‘url’ in the .sequelizerc file. When I execute NODE_ENV=production yarn start, there is an Error in the figure.
Unhandled rejection Error: Error parsing url: mysql://root:QWE!@#qwe123@localhost:3306/hedgedoc

I’m a bit puzzled. mysql://username:password@localhost:3306/hedgedoc should work.
But your password seems to include a @? You could try to encode the @ as %40

Also you want to change this password now.

I just deleted the @ ,but it shows ERROR: getaddrinfo ENOTFOUND root

You might want to have a look here about encoding passwords in URLs: https://serverfault.com/a/1001324