Custom visual "Invalid API Version v2.6.0" error

Hello, I need to modify an old custom visual I built about 2 years ago.  And when I tried to start it or build it, it says

VALIDATION Invalid API Version v2.6.0

I installed [email protected], [email protected]

but it still gives the same error.

in my package.json:

"devDependencies": {
"powerbi-visuals-api": "^2.6.1",
"ts-loader": "6.1.0",
"tslint": "^5.18.0",
"tslint-microsoft-contrib": "^6.2.0",
"typescript": "3.6.3"

I don't want to spend too much time migrating this custom visual viewmodels to 3.x.  Any help, suggestion please?

Thank you.