diff --git a/README.md b/README.md
index 22faea5..184d6be 100644
--- a/README.md
+++ b/README.md
@@ -101,6 +101,7 @@ $ mas lucky twitter
 
 > Please note that this command will not allow you to install (or even purchase) an app for the first time:
 use the `purchase` command in that case.
+> ⛔ The `purchase` command is not supported as of macOS 10.15 Catalina. Please see [Known Issues](#%EF%B8%8F-known-issues).
 
 ```bash
 $ mas purchase 768053424
@@ -148,6 +149,8 @@ Xcode (8.0)
 
 ### 🚏📥 Sign-in
 
+> ⛔ The `signin` command is not supported as of macOS 10.13 High Sierra. Please see [Known Issues](#%EF%B8%8F-known-issues).
+
 To sign into the Mac App Store for the first time run `mas signin`.
 
 ```bash
@@ -156,11 +159,8 @@ $ mas signin mas@example.com
 Password:
 ```
 
-> ⚠️ Due to breaking changes in the underlying API that mas uses to interact with the Mac App Store,
-> the `signin` command has been temporarily disabled on macOS 10.13+ ⛔.
-> For more information on this issue, see [#164](https://github.com/mas-cli/mas/issues/164).
-
-If you experience issues signing in this way, you can ask to signin using a graphical dialog (provided by Mac App Store application):
+If you experience issues signing in this way, you can ask to sign in using a graphical dialog
+(provided by Mac App Store application):
 
 ```bash
 $ mas signin --dialog mas@example.com
@@ -182,6 +182,22 @@ Use `mas signout` to sign out from the Mac App Store.
 then your Mac App Store apps will be included in the Brewfile created. See the [homebrew-bundle]
 docs for more details.
 
+## ⚠️ Known Issues
+
+Over time, Apple has changed the APIs used by `mas` to manage App Store apps, limiting its capabilities. Please sign in
+or purchase apps using the App Store app instead. Subsequent redownloads can be performed with `mas install`.
+
+- ⛔️ The `signin` command is not supported as of macOS 10.13 High Sierra. [#164](https://github.com/mas-cli/mas/issues/164)
+- ⛔️ The `purchase` command is not supported as of macOS 10.15 Catalina. [#289](https://github.com/mas-cli/mas/issues/289)
+- ⛔️ The `account` command is not supported as of macOS 12 Monterey. [#417](https://github.com/mas-cli/mas/issues/417)
+
+The versions `mas` sees from the app bundles on your Mac don't always match the versions reported by the App Store for
+the same app bundles. This leads to some confusion when the `outdated` and `upgrade` commands differ in behavior from
+what is shown as outdated in the App Store app. Further confusing matters, there is often some delay due to CDN
+propagatioon and caching between the time a new app version is released to the App Store, and the time it appears
+available in the App Store app or via the `mas` command. These issues cause symptoms like
+[#384](https://github.com/mas-cli/mas/issues/384) and [#387](https://github.com/mas-cli/mas/issues/387).
+
 ## 💥 When something doesn't work
 
 If you see this error, it's probably because you haven't installed the app through the App Store yet.
diff --git a/Sources/MasKit/Commands/SignIn.swift b/Sources/MasKit/Commands/SignIn.swift
index 77fc128..f1b7cf0 100644
--- a/Sources/MasKit/Commands/SignIn.swift
+++ b/Sources/MasKit/Commands/SignIn.swift
@@ -20,7 +20,9 @@ public struct SignInCommand: CommandProtocol {
     /// Runs the command.
     public func run(_ options: Options) -> Result<Void, MASError> {
         if #available(macOS 10.13, *) {
-            return .failure(.signInDisabled)
+            // Signing in is no longer possible as of High Sierra.
+            // https://github.com/mas-cli/mas/issues/164
+            return .failure(.notSupported)
         }
 
         guard ISStoreAccount.primaryAccount == nil else {
diff --git a/Sources/MasKit/Errors/MASError.swift b/Sources/MasKit/Errors/MASError.swift
index 2f594ce..eeee564 100644
--- a/Sources/MasKit/Errors/MASError.swift
+++ b/Sources/MasKit/Errors/MASError.swift
@@ -9,8 +9,9 @@
 import Foundation
 
 public enum MASError: Error, Equatable {
+    case notSupported
+
     case notSignedIn
-    case signInDisabled
     case signInFailed(error: NSError?)
     case alreadySignedIn
 
@@ -38,12 +39,11 @@ extension MASError: CustomStringConvertible {
         case .notSignedIn:
             return "Not signed in"
 
-        case .signInDisabled:
+        case .notSupported:
             return """
-                The 'signin' command has been disabled on this macOS version. \
-                Please sign into the Mac App Store app manually.
-                For more info see: \
-                https://github.com/mas-cli/mas/issues/164
+                This command is not supported on this macOS version due to changes in macOS. \
+                For more information see: \
+                https://github.com/mas-cli/mas#known-issues
                 """
 
         case .signInFailed(let error):