MySQL 5.5 accepts password but then closes connection

I hope your problem might have been already resolved.

However, I recently had a similar experience and I had to do following to resolve it.

1. Launch MySQL Workbench (Mine was 5.2.36 CE Revision 8542)
2. Double click on a server instance to manage the server instance
3. Goto Users and Privileges
4. Select root or other user you wish to check from the list in "Server Access Management" tab
5. Change the "Limit connectivity to hosts matching:" to IP that you are using to connect OR just change it to "%" to remove the IP restriction.<6> 6. In my case I had to change it to "%" to make it work.

Hope this will be helpful to someone, someday!
Cheers Manish.

Since Zapier is coming in from outside your instance, a possible cause of your problem is the security group for your instance. Most ports on EC2 instances (except the SSH port) are normally blocked by default unless you explicitly open them.

So you would need to open the mysql port 3306 on your instance up to the ip address Zapier is coming in from. (preferably you would not open it up to everyone in the world.)

See Using Amazon RDS/EC2 on the Zapier site, starting from the section where it says Can't Connect to My Database. They continue on to provide specific instructions for the security group settings.

You will also probably need to grant permission on the database using the mysql GRANT command to the user coming in from the Zapier ip address.

Something like this should work :

GRANT ALL PRIVILEGES
ON mydb.*
TO 'user'@'54.86.9.50'
IDENTIFIED BY 'newpassword';

Or you can allow that user to come in from any ip adress like this:

GRANT ALL PRIVILEGES
ON mydb.*
TO 'user'@'%'
IDENTIFIED BY 'newpassword';

(Incoming requests would still be limited to Zapier ip addresses due to the security group settings.)