# Compilation error: TypeError this.app.promise is not a function

**URL:** https://discourse.roots.io/t/compilation-error-typeerror-this-app-promise-is-not-a-function/25826
**Category:** sage
**Tags:** bootstrap, sage10
**Created:** 2023-08-18T13:42:38Z
**Posts:** 3

## Post 1 by @robermendo — 2023-08-18T13:42:39Z

I have done an installation of sage 10, and then I wanted to change tailwind for bootstrap. I have followed the official tutorial ([Replacing Tailwind CSS with Bootstrap | Sage Docs | Roots](https://roots.io/sage/docs/replacing-tailwind-with-bootstrap/)) and at first everything went well, but when compiling I got the following error:  
TypeError  
this.app.promise is not a function.

I have tried multiple ways to fix it but to no avail. Does anyone have an idea how to fix it?

---

## Post 2 by @mikespainhower — 2023-08-18T16:00:14Z

Please [share your code](https://discourse.roots.io/t/how-to-best-ask-questions-on-this-forum/24582#post-your-code-error-messages-and-logs-4), e.g. `package.json`, `bud.config.js`, and `app.js`

---

## Post 3 by @andrewmarksmith — 2023-09-04T11:21:29Z

I was having the same issue but went back and read the [Using SASS docs](https://roots.io/sage/docs/sass/) which warn:

` **Note:** Verify that all Bud packages and the`@roots/sage`package versions are the same in your`package.json` to prevent build errors.`

I was using later versions of `@roots/bud-sass` and `@roots/bud-stylelint`. I reinstalled to match `@roots/bud` and compiled without error.

```
"devDependencies": {
    "@roots/bud": "6.7.3",
    "@roots/bud-sass": "6.7.3",
    "@roots/bud-stylelint": "6.7.3",
    "@roots/sage": "6.7.3"
  },
```