diff --git a/__test__/common/github/AccessTokenRefreshingGitHubClient.test.ts b/__test__/common/github/AccessTokenRefreshingGitHubClient.test.ts
index c8c7d21a..7913e1c3 100644
--- a/__test__/common/github/AccessTokenRefreshingGitHubClient.test.ts
+++ b/__test__/common/github/AccessTokenRefreshingGitHubClient.test.ts
@@ -27,7 +27,10 @@ test("It forwards a GraphQL request", async () => {
     async getPullRequestComments() {
       return []
     },
-    async addCommentToPullRequest() {}
+    async addCommentToPullRequest() {},
+    async getOrganizationMembershipStatus() {
+      return { state: "active" }
+    }
   })
   const request: GraphQLQueryRequest = {
     query: "foo",
@@ -58,7 +61,10 @@ test("It forwards a request to get the repository content", async () => {
     async getPullRequestComments() {
       return []
     },
-    async addCommentToPullRequest() {}
+    async addCommentToPullRequest() {},
+    async getOrganizationMembershipStatus() {
+      return { state: "active" }
+    }
   })
   const request: GetRepositoryContentRequest = {
     repositoryOwner: "foo",
@@ -91,7 +97,10 @@ test("It forwards a request to get comments to a pull request", async () => {
       forwardedRequest = request
       return []
     },
-    async addCommentToPullRequest() {}
+    async addCommentToPullRequest() {},
+    async getOrganizationMembershipStatus() {
+      return { state: "active" }
+    }
   })
   const request: GetPullRequestCommentsRequest = {
     appInstallationId: 1234,
@@ -125,6 +134,9 @@ test("It forwards a request to add a comment to a pull request", async () => {
     },
     async addCommentToPullRequest(request: AddCommentToPullRequestRequest) {
       forwardedRequest = request
+    },
+    async getOrganizationMembershipStatus() {
+      return { state: "active" }
     }
   })
   const request: AddCommentToPullRequestRequest = {
@@ -164,7 +176,10 @@ test("It retries with a refreshed access token when receiving HTTP 401", async (
     async getPullRequestComments() {
       return []
     },
-    async addCommentToPullRequest() {}
+    async addCommentToPullRequest() {},
+    async getOrganizationMembershipStatus() {
+      return { state: "active" }
+    }
   })
   const request: GraphQLQueryRequest = {
     query: "foo",
@@ -195,7 +210,10 @@ test("It only retries a request once when receiving HTTP 401", async () => {
     async getPullRequestComments() {
       return []
     },
-    async addCommentToPullRequest() {}
+    async addCommentToPullRequest() {},
+    async getOrganizationMembershipStatus() {
+      return { state: "active" }
+    }
   })
   const request: GraphQLQueryRequest = {
     query: "foo",
@@ -229,7 +247,10 @@ test("It does not refresh an access token when the initial request was successfu
     async getPullRequestComments() {
       return []
     },
-    async addCommentToPullRequest() {}
+    async addCommentToPullRequest() {},
+    async getOrganizationMembershipStatus() {
+      return { state: "active" }
+    }
   })
   const request: GraphQLQueryRequest = {
     query: "foo",
diff --git a/__test__/common/session/GitHubOrganizationSessionValidator.test.ts b/__test__/common/session/GitHubOrganizationSessionValidator.test.ts
new file mode 100644
index 00000000..105039de
--- /dev/null
+++ b/__test__/common/session/GitHubOrganizationSessionValidator.test.ts
@@ -0,0 +1,143 @@
+import {
+  GetOrganizationMembershipStatusRequest
+} from "../../../src/common/github/IGitHubClient"
+import GitHubOrganizationSessionValidator from "../../../src/common/session/GitHubOrganizationSessionValidator"
+
+test("It requests organization membership status for the specified organization", async () => {
+  let queriedOrganizationName: string | undefined
+  const sut = new GitHubOrganizationSessionValidator(
+    {
+      async graphql() {
+        return {}
+      },
+      async getRepositoryContent() {
+        return { downloadURL: "https://example.com" }
+      },
+      async getPullRequestComments() {
+        return []
+      },
+      async addCommentToPullRequest() {},
+      async getOrganizationMembershipStatus(request: GetOrganizationMembershipStatusRequest) {
+        queriedOrganizationName = request.organizationName
+        return { state: "active" }
+      }
+    },
+    "foo"
+  )
+  await sut.validateSession()
+  expect(queriedOrganizationName).toBe("foo")
+})
+
+test("It considers session valid when membership state is \"active\"", async () => {
+  const sut = new GitHubOrganizationSessionValidator(
+    {
+      async graphql() {
+        return {}
+      },
+      async getRepositoryContent() {
+        return { downloadURL: "https://example.com" }
+      },
+      async getPullRequestComments() {
+        return []
+      },
+      async addCommentToPullRequest() {},
+      async getOrganizationMembershipStatus() {
+        return { state: "active" }
+      }
+    },
+    "foo"
+  )
+  const isSessionValid = await sut.validateSession()
+  expect(isSessionValid).toBeTruthy()
+})
+
+test("It considers session invalid when membership state is \"pending\"", async () => {
+  const sut = new GitHubOrganizationSessionValidator(
+    {
+      async graphql() {
+        return {}
+      },
+      async getRepositoryContent() {
+        return { downloadURL: "https://example.com" }
+      },
+      async getPullRequestComments() {
+        return []
+      },
+      async addCommentToPullRequest() {},
+      async getOrganizationMembershipStatus() {
+        return { state: "pending" }
+      }
+    },
+    "foo"
+  )
+  const isSessionValid = await sut.validateSession()
+  expect(isSessionValid).toBeFalsy()
+})
+
+test("It considers session invalid when receiving HTTP 404, indicating user is not member of the organization", async () => {
+  const sut = new GitHubOrganizationSessionValidator(
+    {
+      async graphql() {
+        return {}
+      },
+      async getRepositoryContent() {
+        return { downloadURL: "https://example.com" }
+      },
+      async getPullRequestComments() {
+        return []
+      },
+      async addCommentToPullRequest() {},
+      async getOrganizationMembershipStatus() {
+        throw { status: 404, message: "User is not member of organization"}
+      }
+    },
+    "foo"
+  )
+  const isSessionValid = await sut.validateSession()
+  expect(isSessionValid).toBeFalsy()
+})
+
+test("It considers session invalid when receiving HTTP 404, indicating that the organization has blocked the GitHub app", async () => {
+  const sut = new GitHubOrganizationSessionValidator(
+    {
+      async graphql() {
+        return {}
+      },
+      async getRepositoryContent() {
+        return { downloadURL: "https://example.com" }
+      },
+      async getPullRequestComments() {
+        return []
+      },
+      async addCommentToPullRequest() {},
+      async getOrganizationMembershipStatus() {
+        throw { status: 403, message: "Organization has blocked GitHub app"}
+      }
+    },
+    "foo"
+  )
+  const isSessionValid = await sut.validateSession()
+  expect(isSessionValid).toBeFalsy()
+})
+
+test("It forwards error when getting membership status throws unknown error", async () => {
+  const sut = new GitHubOrganizationSessionValidator(
+    {
+      async graphql() {
+        return {}
+      },
+      async getRepositoryContent() {
+        return { downloadURL: "https://example.com" }
+      },
+      async getPullRequestComments() {
+        return []
+      },
+      async addCommentToPullRequest() {},
+      async getOrganizationMembershipStatus() {
+        throw { status: 500 }
+      }
+    },
+    "foo"
+  )
+  await expect(sut.validateSession()).rejects.toEqual({ status: 500 })
+})
\ No newline at end of file
diff --git a/__test__/projects/SessionValidatingProjectDataSource.test.ts b/__test__/projects/SessionValidatingProjectDataSource.test.ts
new file mode 100644
index 00000000..f0f96dc7
--- /dev/null
+++ b/__test__/projects/SessionValidatingProjectDataSource.test.ts
@@ -0,0 +1,46 @@
+import SessionValidatingProjectDataSource from "../../src/features/projects/domain/SessionValidatingProjectDataSource"
+
+test("It validates the session", async () => {
+  let didValidateSession = false
+  const sut = new SessionValidatingProjectDataSource({
+    async validateSession() {
+      didValidateSession = true
+      return true
+    },
+  }, {
+    async getProjects() {
+      return []
+    }
+  })
+  await sut.getProjects()
+  expect(didValidateSession).toBeTruthy()
+})
+
+test("It fetches projects when session is valid", async () => {
+  let didFetchProjects = false
+  const sut = new SessionValidatingProjectDataSource({
+    async validateSession() {
+      return true
+    },
+  }, {
+    async getProjects() {
+      didFetchProjects = true
+      return []
+    }
+  })
+  await sut.getProjects()
+  expect(didFetchProjects).toBeTruthy()
+})
+
+test("It throws error when session is invalid", async () => {
+  const sut = new SessionValidatingProjectDataSource({
+    async validateSession() {
+      return false
+    },
+  }, {
+    async getProjects() {
+      return []
+    }
+  })
+  expect(sut.getProjects()).rejects.toThrowError()
+})
diff --git a/src/app/api/user/projects/route.ts b/src/app/api/user/projects/route.ts
index a0ac3816..799f13f6 100644
--- a/src/app/api/user/projects/route.ts
+++ b/src/app/api/user/projects/route.ts
@@ -1,6 +1,6 @@
 import { NextResponse } from "next/server"
 import { projectDataSource } from "@/composition"
-import { UnauthorizedError } from "@/features/auth/domain/AuthError"
+import { UnauthorizedError, InvalidSessionError } from "@/common/errors"
 
 export async function GET() {
   try {
@@ -8,20 +8,17 @@ export async function GET() {
     return NextResponse.json({projects})
   } catch (error) {
     if (error instanceof UnauthorizedError) {
-      return NextResponse.json({
-        status: 401,
-        message: error.message
-      }, { status: 401 })
+      return errorResponse(401, error.message)
+    } else if (error instanceof InvalidSessionError) {
+      return errorResponse(403, error.message)
     } else if (error instanceof Error) {
-      return NextResponse.json({
-        status: 500,
-        message: error.message
-      }, { status: 500 })
+      return errorResponse(500, error.message)
     } else {
-      return NextResponse.json({
-        status: 500,
-        message: "Unknown error"
-      }, { status: 500 })
+      return errorResponse(500, "Unknown error")
     }
   }
 }
+
+function errorResponse(status: number, message: string): NextResponse {
+  return NextResponse.json({ status, message }, { status })
+}
diff --git a/src/app/invalid-session/page.tsx b/src/app/invalid-session/page.tsx
new file mode 100644
index 00000000..ee33fec5
--- /dev/null
+++ b/src/app/invalid-session/page.tsx
@@ -0,0 +1,5 @@
+import InvalidSessionPage from "@/features/auth/view/InvalidSessionPage"
+
+export default async function Page() {
+  return <InvalidSessionPage/>
+}
diff --git a/src/app/layout.tsx b/src/app/layout.tsx
index 6d89e3d4..1760b426 100644
--- a/src/app/layout.tsx
+++ b/src/app/layout.tsx
@@ -4,7 +4,7 @@ import { UserProvider } from "@auth0/nextjs-auth0/client"
 import { config as fontAwesomeConfig } from "@fortawesome/fontawesome-svg-core"
 import { CssBaseline } from "@mui/material"
 import ThemeRegistry from "@/common/theme/ThemeRegistry"
-import ErrorHandler from "@/common/errorHandling/client/ErrorHandler"
+import ErrorHandler from "@/common/errors/client/ErrorHandler"
 import "@fortawesome/fontawesome-svg-core/styles.css"
 
 fontAwesomeConfig.autoAddCss = false
diff --git a/src/common/errorHandling/client/ErrorHandler.tsx b/src/common/errors/client/ErrorHandler.tsx
similarity index 66%
rename from src/common/errorHandling/client/ErrorHandler.tsx
rename to src/common/errors/client/ErrorHandler.tsx
index 83b68d45..20ba19a3 100644
--- a/src/common/errorHandling/client/ErrorHandler.tsx
+++ b/src/common/errors/client/ErrorHandler.tsx
@@ -9,10 +9,13 @@ export default function ErrorHandler({
   children: React.ReactNode
 }) {
   const onSWRError = (error: FetcherError) => {
+    if (typeof window === "undefined") {
+      return
+    }
     if (error.status == 401) {
-      if (typeof window !== "undefined") {
-        window.location.href = "/api/auth/logout"
-      }
+      window.location.href = "/api/auth/logout"
+    } else if (error.status == 403) {
+      window.location.href = "/invalid-session"
     }
   }
   return (
diff --git a/src/common/errors/index.ts b/src/common/errors/index.ts
new file mode 100644
index 00000000..74acb8d0
--- /dev/null
+++ b/src/common/errors/index.ts
@@ -0,0 +1,2 @@
+export class UnauthorizedError extends Error {}
+export class InvalidSessionError extends Error {}
diff --git a/src/common/github/AccessTokenRefreshingGitHubClient.ts b/src/common/github/AccessTokenRefreshingGitHubClient.ts
index e9a3a29a..e5e4a9e7 100644
--- a/src/common/github/AccessTokenRefreshingGitHubClient.ts
+++ b/src/common/github/AccessTokenRefreshingGitHubClient.ts
@@ -4,6 +4,8 @@ import IGitHubClient, {
   GraphQlQueryResponse,
   GetRepositoryContentRequest,
   GetPullRequestCommentsRequest,
+  GetOrganizationMembershipStatusRequest,
+  GetOrganizationMembershipStatusRequestResponse,
   AddCommentToPullRequestRequest,
   RepositoryContent,
   PullRequestComment
@@ -60,6 +62,14 @@ export default class AccessTokenRefreshingGitHubClient implements IGitHubClient
     })
   }
   
+  async getOrganizationMembershipStatus(
+    request: GetOrganizationMembershipStatusRequest
+  ): Promise<GetOrganizationMembershipStatusRequestResponse> {
+    return await this.send(async () => {
+      return await this.gitHubClient.getOrganizationMembershipStatus(request)
+    })
+  }
+  
   private async send<T>(fn: () => Promise<T>): Promise<T> {
     const accessToken = await this.accessTokenReader.getAccessToken()
     try {
diff --git a/src/common/github/GitHubClient.ts b/src/common/github/GitHubClient.ts
index 2b03cbe2..cec899e9 100644
--- a/src/common/github/GitHubClient.ts
+++ b/src/common/github/GitHubClient.ts
@@ -6,6 +6,8 @@ import IGitHubClient, {
   GetRepositoryContentRequest,
   GetPullRequestCommentsRequest,
   AddCommentToPullRequestRequest,
+  GetOrganizationMembershipStatusRequest,
+  GetOrganizationMembershipStatusRequestResponse,
   RepositoryContent,
   PullRequestComment
 } from "./IGitHubClient"
@@ -90,4 +92,15 @@ export default class GitHubClient implements IGitHubClient {
       body: request.body
     })
   }
+  
+  async getOrganizationMembershipStatus(
+    request: GetOrganizationMembershipStatusRequest
+  ): Promise<GetOrganizationMembershipStatusRequestResponse> {
+    const accessToken = await this.accessTokenReader.getAccessToken()
+    const octokit = new Octokit({ auth: accessToken })
+    const response = await octokit.rest.orgs.getMembershipForAuthenticatedUser({
+      org: request.organizationName
+    })
+    return { state: response.data.state }
+  }
 }
diff --git a/src/common/github/IGitHubClient.ts b/src/common/github/IGitHubClient.ts
index 9537786e..1b349fc6 100644
--- a/src/common/github/IGitHubClient.ts
+++ b/src/common/github/IGitHubClient.ts
@@ -40,9 +40,18 @@ export type AddCommentToPullRequestRequest = {
   readonly body: string
 }
 
+export type GetOrganizationMembershipStatusRequest = {
+  readonly organizationName: string
+}
+
+export type GetOrganizationMembershipStatusRequestResponse = {
+  readonly state: "active" | "pending"
+}
+
 export default interface IGitHubClient {
   graphql(request: GraphQLQueryRequest): Promise<GraphQlQueryResponse>
   getRepositoryContent(request: GetRepositoryContentRequest): Promise<RepositoryContent>
   getPullRequestComments(request: GetPullRequestCommentsRequest): Promise<PullRequestComment[]>
   addCommentToPullRequest(request: AddCommentToPullRequestRequest): Promise<void>
+  getOrganizationMembershipStatus(request: GetOrganizationMembershipStatusRequest): Promise<GetOrganizationMembershipStatusRequestResponse>
 }
diff --git a/src/common/session/Auth0Session.ts b/src/common/session/Auth0Session.ts
index 4131b040..0971235b 100644
--- a/src/common/session/Auth0Session.ts
+++ b/src/common/session/Auth0Session.ts
@@ -1,6 +1,6 @@
 import { getSession } from "@auth0/nextjs-auth0"
+import { UnauthorizedError } from "@/common/errors"
 import ISession from "./ISession"
-import { UnauthorizedError } from "@/features/auth/domain/AuthError"
 
 export default class Auth0Session implements ISession {
   async getUserId(): Promise<string> {
diff --git a/src/common/session/GitHubOrganizationSessionValidator.ts b/src/common/session/GitHubOrganizationSessionValidator.ts
new file mode 100644
index 00000000..308ff043
--- /dev/null
+++ b/src/common/session/GitHubOrganizationSessionValidator.ts
@@ -0,0 +1,34 @@
+import IGitHubClient from "../github/IGitHubClient"
+import ISessionValidator from "./ISessionValidator"
+
+export default class GitHubOrganizationSessionValidator implements ISessionValidator {
+  private readonly gitHubClient: IGitHubClient
+  private readonly acceptedOrganization: string
+  
+  constructor(gitHubClient: IGitHubClient, acceptedOrganization: string) {
+    this.gitHubClient = gitHubClient
+    this.acceptedOrganization = acceptedOrganization
+  }
+  
+  async validateSession(): Promise<boolean> {
+    try {
+      const response = await this.gitHubClient.getOrganizationMembershipStatus({
+        organizationName: this.acceptedOrganization
+      })
+      return response.state == "active"
+    /* eslint-disable-next-line  @typescript-eslint/no-explicit-any */
+    } catch (error: any) {
+      if (error.status) {
+        if (error.status == 404) {
+          return false
+        } else if (error.status == 403) {
+          return false
+        } else  {
+          throw error
+        }
+      } else {
+        throw error
+      }
+    }
+  }
+}
diff --git a/src/common/session/ISessionValidator.ts b/src/common/session/ISessionValidator.ts
new file mode 100644
index 00000000..b51cd5e6
--- /dev/null
+++ b/src/common/session/ISessionValidator.ts
@@ -0,0 +1,3 @@
+export default interface ISessionValidator {
+  validateSession(): Promise<boolean>
+}
diff --git a/src/composition.ts b/src/composition.ts
index 37a60313..dcfac50c 100644
--- a/src/composition.ts
+++ b/src/composition.ts
@@ -4,6 +4,7 @@ import Auth0Session from "@/common/session/Auth0Session"
 import CachingProjectDataSource from "@/features/projects/domain/CachingProjectDataSource"
 import GitHubClient from "@/common/github/GitHubClient"
 import GitHubOAuthTokenRefresher from "@/features/auth/data/GitHubOAuthTokenRefresher"
+import GitHubOrganizationSessionValidator from "@/common/session/GitHubOrganizationSessionValidator"
 import GitHubProjectDataSource from "@/features/projects/data/GitHubProjectDataSource"
 import InitialOAuthTokenService from "@/features/auth/domain/InitialOAuthTokenService"
 import KeyValueUserDataRepository from "@/common/userData/KeyValueUserDataRepository"
@@ -15,6 +16,7 @@ import SessionDataRepository from "@/common/userData/SessionDataRepository"
 import SessionMutexFactory from "@/common/mutex/SessionMutexFactory"
 import SessionOAuthTokenRepository from "@/features/auth/domain/SessionOAuthTokenRepository"
 import SessionProjectRepository from "@/features/projects/domain/SessionProjectRepository"
+import SessionValidatingProjectDataSource from "@/features/projects/domain/SessionValidatingProjectDataSource"
 import OAuthTokenRepository from "@/features/auth/domain/OAuthTokenRepository"
 import authLogoutHandler from "@/common/authHandler/logout"
 
@@ -70,6 +72,11 @@ export const gitHubClient = new AccessTokenRefreshingGitHubClient(
   })
 )
 
+export const sessionValidator = new GitHubOrganizationSessionValidator(
+  gitHubClient,
+  GITHUB_ORGANIZATION_NAME
+)
+
 export const sessionProjectRepository = new SessionProjectRepository(
   new SessionDataRepository(
     new Auth0Session(),
@@ -81,9 +88,12 @@ export const sessionProjectRepository = new SessionProjectRepository(
 )
 
 export const projectDataSource = new CachingProjectDataSource(
-  new GitHubProjectDataSource(
-    gitHubClient,
-    GITHUB_ORGANIZATION_NAME
+  new SessionValidatingProjectDataSource(
+    sessionValidator,
+    new GitHubProjectDataSource(
+      gitHubClient,
+      GITHUB_ORGANIZATION_NAME
+    )
   ),
   sessionProjectRepository
 )
diff --git a/src/features/auth/data/Auth0RefreshTokenReader.ts b/src/features/auth/data/Auth0RefreshTokenReader.ts
index 57bf2cde..79fd6bfb 100644
--- a/src/features/auth/data/Auth0RefreshTokenReader.ts
+++ b/src/features/auth/data/Auth0RefreshTokenReader.ts
@@ -1,6 +1,6 @@
 import { ManagementClient } from "auth0"
+import { UnauthorizedError } from "@/common/errors"
 import IRefreshTokenReader from "../domain/IRefreshTokenReader"
-import { UnauthorizedError } from "../domain/AuthError"
 
 interface Auth0RefreshTokenReaderConfig {
   domain: string
diff --git a/src/features/auth/data/GitHubOAuthTokenRefresher.ts b/src/features/auth/data/GitHubOAuthTokenRefresher.ts
index 68dd12c4..d5e88607 100644
--- a/src/features/auth/data/GitHubOAuthTokenRefresher.ts
+++ b/src/features/auth/data/GitHubOAuthTokenRefresher.ts
@@ -1,6 +1,6 @@
+import { UnauthorizedError } from "@/common/errors"
 import OAuthToken from "../domain/OAuthToken"
 import IOAuthTokenRefresher from "../domain/IOAuthTokenRefresher"
-import { UnauthorizedError } from "../domain/AuthError"
 
 export interface GitHubOAuthTokenRefresherConfig {
   readonly clientId: string
diff --git a/src/features/auth/domain/AuthError.ts b/src/features/auth/domain/AuthError.ts
deleted file mode 100644
index 2e482071..00000000
--- a/src/features/auth/domain/AuthError.ts
+++ /dev/null
@@ -1 +0,0 @@
-export class UnauthorizedError extends Error {}
diff --git a/src/features/auth/domain/OAuthTokenRepository.ts b/src/features/auth/domain/OAuthTokenRepository.ts
index d8bdfe17..fd416386 100644
--- a/src/features/auth/domain/OAuthTokenRepository.ts
+++ b/src/features/auth/domain/OAuthTokenRepository.ts
@@ -1,7 +1,7 @@
 import ZodJSONCoder from "@/common/utils/ZodJSONCoder"
 import IUserDataRepository from "@/common/userData/IUserDataRepository"
+import { UnauthorizedError } from "@/common/errors"
 import IOAuthTokenRepository from "./IOAuthTokenRepository"
-import { UnauthorizedError } from "./AuthError"
 import OAuthToken, { OAuthTokenSchema } from "./OAuthToken"
 
 export default class OAuthTokenRepository implements IOAuthTokenRepository {
diff --git a/src/features/auth/domain/SessionOAuthTokenRepository.ts b/src/features/auth/domain/SessionOAuthTokenRepository.ts
index c7942598..2f5d0905 100644
--- a/src/features/auth/domain/SessionOAuthTokenRepository.ts
+++ b/src/features/auth/domain/SessionOAuthTokenRepository.ts
@@ -1,7 +1,7 @@
+import { UnauthorizedError } from "../../../common/errors"
 import ZodJSONCoder from "../../../common/utils/ZodJSONCoder"
 import ISessionDataRepository from "@/common/userData/ISessionDataRepository"
 import ISessionOAuthTokenRepository from "./SessionOAuthTokenRepository"
-import { UnauthorizedError } from "./AuthError"
 import OAuthToken, { OAuthTokenSchema } from "./OAuthToken"
 
 export default class SessionOAuthTokenRepository implements ISessionOAuthTokenRepository {
diff --git a/src/features/auth/view/InvalidSessionPage.tsx b/src/features/auth/view/InvalidSessionPage.tsx
new file mode 100644
index 00000000..99292a13
--- /dev/null
+++ b/src/features/auth/view/InvalidSessionPage.tsx
@@ -0,0 +1,22 @@
+import { redirect } from "next/navigation"
+import { sessionValidator } from "@/composition"
+import InvalidSession from "./client/InvalidSession"
+
+const {
+  NEXT_PUBLIC_SHAPE_DOCS_TITLE,
+  GITHUB_ORGANIZATION_NAME
+} = process.env
+
+export default async function InvalidSessionPage() {
+  const isSessionValid = await sessionValidator.validateSession()
+  if (isSessionValid) {
+    // User ended up here by mistake so lets send them to the front page.
+    redirect("/")
+  }
+  return (
+    <InvalidSession
+      siteName={NEXT_PUBLIC_SHAPE_DOCS_TITLE}
+      organizationName={GITHUB_ORGANIZATION_NAME}
+    />
+  )
+}
diff --git a/src/features/auth/view/client/InvalidSession.tsx b/src/features/auth/view/client/InvalidSession.tsx
new file mode 100644
index 00000000..76cf8416
--- /dev/null
+++ b/src/features/auth/view/client/InvalidSession.tsx
@@ -0,0 +1,32 @@
+"use client"
+
+import { Button, Stack, Typography } from "@mui/material"
+
+export default function InvalidSession({
+  siteName,
+  organizationName
+}: {
+  siteName: string
+  organizationName: string
+}) {
+  const navigateToFrontPage = () => {
+    if (typeof window !== "undefined") {
+      window.location.href = "/api/auth/logout"
+    }
+  }
+  return (
+    <Stack alignItems="center" justifyContent="center" sx={{ width: "100%", height: "100%" }}>
+      <Stack direction="column" spacing={3} alignItems="center" sx={{ margin: 2, maxWidth: "500px" }}>
+        <Typography variant="h6" align="center">
+          Your account does not have access to {siteName}
+        </Typography>
+        <Typography align="center">
+          Access to {siteName} requires that your account is an active member of the <strong>{organizationName}</strong> organization on GitHub.
+        </Typography>
+        <Button variant="contained" onClick={navigateToFrontPage}>
+          Log out
+        </Button>
+      </Stack>
+    </Stack>
+  )
+}
diff --git a/src/features/projects/domain/SessionValidatingProjectDataSource.ts b/src/features/projects/domain/SessionValidatingProjectDataSource.ts
new file mode 100644
index 00000000..942d0859
--- /dev/null
+++ b/src/features/projects/domain/SessionValidatingProjectDataSource.ts
@@ -0,0 +1,25 @@
+import { InvalidSessionError } from "../../../common/errors"
+import ISessionValidator from "@/common/session/ISessionValidator"
+import IProjectDataSource from "../domain/IProjectDataSource"
+import Project from "../domain/Project"
+
+export default class SessionValidatingProjectDataSource implements IProjectDataSource {
+  private readonly sessionValidator: ISessionValidator
+  private readonly projectDataSource: IProjectDataSource
+  
+  constructor(
+    sessionValidator: ISessionValidator,
+    projectDataSource: IProjectDataSource
+  ) {
+    this.sessionValidator = sessionValidator
+    this.projectDataSource = projectDataSource
+  }
+  
+  async getProjects(): Promise<Project[]> {
+    const isValid = await this.sessionValidator.validateSession()
+    if (!isValid) {
+      throw new InvalidSessionError()
+    }
+    return await this.projectDataSource.getProjects()
+  }
+}