If you read the error it advises you on what steps to take.
It’s telling you to add the following environment variable then run the command again:
SHOPIFY_CLI_STACKTRACE=1
To do that, if you’re on some kind of Linux setup is as simple as running:
export SHOPIFY_CLI_STACKTRACE=1
Or if you’re in windows and using PowerShell, run this command:
$env:SHOPIFY_CLI_STACKTRACE=1
Or if you’re on Windows running a normal command prompt:
set SHOPIFY_CLI_STACKTRACE=1
Now you’ve got that environment variable in your current shell session - you’ll run the command again and you should see a more detailed error:
shopify theme serve
If you post the output of that we should be able to give you some more guidance on the root cause of the error.