eth-brownie: Unable to expand environment variable in host setting

Question

When running a script:

brownie run scripts/deploy.py --network kovan

I receive this error:

raise ValueError(f"Unable to expand environment variable in host setting: ‘{uri}’”)
ValueError: Unable to expand environment variable in host setting: ‘https://kovan.infura.io/v3/$WEB3_INFURA_PROJECT_ID

What am I doing wrong?

Answer 1

Typically, this means your environment variables are not set correctly, and it looks like in this case it's your WEB3_INFURA_PROJECT_ID.

Solution 1

You can fix it by setting the variable in your .env file and adding dotenv: .env to your brownie-config.yaml.

brownie-config.yaml:

dotenv: .env

.env:

export WEB3_INFURA_PROJECT_ID=YOUR_PROJECT_ID_HERE

Remember to save these files.

Additionally, you should be on at least brownie version v1.14.6. You can find out what version you're on with:

brownie --version

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Solution 2

If you know how to set environment variables you might want to check if you're setting them correctly. If you're on a linux-like environment, you can do:

source .env

To set them.

Answer 2

I've had this error for days and have seen it posted alot online. I was simply 1 directory up from where I needed to be - I followed the Patrick Collins tutorial very closey with the addition of setting up a virtual env, so maybe others are simply having the same problem I had.

I was originally in a directory "\demos\web3 brownie" which contained a folder called "brownie" and my python virtual env files.

The script is now running when I'm in directory "\demos\web3 brownie\brownie" which contains the brownie build, script, contract directories

Answer 3

Sometimes it can be as simple as a typo error, such as improperly naming your files, such as "browni-config.yaml" when it should be "brownie-config.yaml".

Answer 4

if you are sure you set the .env correctly you can try sourcing your .env file in the terminal:

source .env

and then try running your script again.

Answer 5

I was having the same problem as you , also with PRIVATE_KEY associating. What I've done is copy the .env field in the scripts folder , adding also dotenv : .env to brownie-config.yaml