diff --git a/apps/app-frontend/src/App.vue b/apps/app-frontend/src/App.vue
index f402277b6..601d7172a 100644
--- a/apps/app-frontend/src/App.vue
+++ b/apps/app-frontend/src/App.vue
@@ -65,6 +65,7 @@ import IncompatibilityWarningModal from '@/components/ui/install_flow/Incompatib
 import InstallConfirmModal from '@/components/ui/install_flow/InstallConfirmModal.vue'
 import ModInstallModal from '@/components/ui/install_flow/ModInstallModal.vue'
 import InstanceCreationModal from '@/components/ui/InstanceCreationModal.vue'
+import MinecraftAuthErrorModal from '@/components/ui/minecraft-auth-error-modal/MinecraftAuthErrorModal.vue'
 import AppSettingsModal from '@/components/ui/modal/AppSettingsModal.vue'
 import AuthGrantFlowWaitModal from '@/components/ui/modal/AuthGrantFlowWaitModal.vue'
 import NavButton from '@/components/ui/NavButton.vue'
@@ -388,6 +389,7 @@ loading.setEnabled(false)
 
 const error = useError()
 const errorModal = ref()
+const minecraftAuthErrorModal = ref()
 
 const install = useInstall()
 const modInstallModal = ref()
@@ -466,6 +468,7 @@ onMounted(() => {
 	invoke('show_window')
 
 	error.setErrorModal(errorModal.value)
+	error.setMinecraftAuthErrorModal(minecraftAuthErrorModal.value)
 
 	install.setIncompatibilityWarningModal(incompatibilityWarningModal)
 	install.setInstallConfirmModal(installConfirmModal)
@@ -1131,6 +1134,7 @@ provideAppUpdateDownloadProgress(appUpdateDownload)
 	<I18nDebugPanel />
 	<NotificationPanel has-sidebar />
 	<ErrorModal ref="errorModal" />
+	<MinecraftAuthErrorModal ref="minecraftAuthErrorModal" />
 	<ModInstallModal ref="modInstallModal" />
 	<IncompatibilityWarningModal ref="incompatibilityWarningModal" />
 	<InstallConfirmModal ref="installConfirmModal" />
diff --git a/apps/app-frontend/src/components/ui/ErrorModal.vue b/apps/app-frontend/src/components/ui/ErrorModal.vue
index 17a9dffc7..45392b297 100644
--- a/apps/app-frontend/src/components/ui/ErrorModal.vue
+++ b/apps/app-frontend/src/components/ui/ErrorModal.vue
@@ -33,6 +33,7 @@ const metadata = ref({})
 
 defineExpose({
 	async show(errorVal, context, canClose = true, source = null) {
+		console.log(errorVal, context, canClose, source)
 		closable.value = canClose
 
 		if (errorVal.message && errorVal.message.includes('Minecraft authentication error:')) {
diff --git a/apps/app-frontend/src/components/ui/minecraft-auth-error-modal/MinecraftAuthErrorModal.vue b/apps/app-frontend/src/components/ui/minecraft-auth-error-modal/MinecraftAuthErrorModal.vue
new file mode 100644
index 000000000..16c2c9d2f
--- /dev/null
+++ b/apps/app-frontend/src/components/ui/minecraft-auth-error-modal/MinecraftAuthErrorModal.vue
@@ -0,0 +1,184 @@
+<script setup lang="ts">
+import {
+	CheckIcon,
+	CopyIcon,
+	DropdownIcon,
+	LogInIcon,
+	MessagesSquareIcon,
+	WrenchIcon,
+} from '@modrinth/assets'
+import { Admonition, ButtonStyled, Collapsible, NewModal } from '@modrinth/ui'
+import { computed, ref } from 'vue'
+
+import { login as login_flow, set_default_user } from '@/helpers/auth.js'
+import { handleSevereError } from '@/store/error.js'
+
+import { type MinecraftAuthError, minecraftAuthErrors } from './minecraft-auth-errors'
+
+const modal = ref<InstanceType<typeof NewModal>>()
+const rawError = ref<string>('')
+const matchedError = ref<MinecraftAuthError | null>(null)
+const debugCollapsed = ref(true)
+const copied = ref(false)
+const loadingSignIn = ref(false)
+
+function show(errorVal: { message?: string }) {
+	rawError.value = errorVal?.message ?? String(errorVal)
+
+	matchedError.value = minecraftAuthErrors.find((e) => rawError.value.includes(e.errorCode)) ?? null
+
+	debugCollapsed.value = true
+	modal.value?.show()
+}
+
+function hide() {
+	modal.value?.hide()
+}
+
+defineExpose({
+	show,
+	hide,
+})
+
+async function signInAgain() {
+	try {
+		loadingSignIn.value = true
+		const loggedIn = await login_flow()
+		if (loggedIn) {
+			await set_default_user(loggedIn.profile.id)
+		}
+		loadingSignIn.value = false
+		modal.value?.hide()
+	} catch (err) {
+		loadingSignIn.value = false
+		handleSevereError(err)
+	}
+}
+
+const debugInfo = computed(() => rawError.value || 'No error message.')
+
+async function copyToClipboard(text: string) {
+	await navigator.clipboard.writeText(text)
+	copied.value = true
+	setTimeout(() => {
+		copied.value = false
+	}, 3000)
+}
+</script>
+
+<template>
+	<NewModal ref="modal" header="Sign in Failed" :max-width="'548px'">
+		<div class="flex flex-col gap-6">
+			<Admonition
+				type="warning"
+				body="	We couldn't sign you into your Microsoft account. This may be due to account restrictions or
+				regional limitations."
+			>
+			</Admonition>
+
+			<!-- Matched error details -->
+			<div class="bg-surface-2 rounded-2xl p-4 px-5 flex flex-col gap-3">
+				<template v-if="matchedError">
+					<div class="flex flex-col gap-1.5">
+						<h3 class="text-base font-bold m-0">What we think happened</h3>
+						<p class="text-sm text-secondary m-0">
+							{{ matchedError.whatHappened }}
+						</p>
+					</div>
+
+					<div class="flex flex-col gap-1.5">
+						<h3 class="text-base font-bold m-0">How to fix it</h3>
+						<ol class="list-none flex flex-col gap-2 m-0 pl-0">
+							<li
+								v-for="(step, index) in matchedError.stepsToFix"
+								:key="index"
+								class="flex items-baseline gap-2"
+							>
+								<span
+									class="inline-flex items-center justify-center shrink-0 w-5 h-5 rounded-full bg-surface-4 border border-solid border-surface-5 text-xs font-medium"
+								>
+									{{ index + 1 }}
+								</span>
+								<!-- eslint-disable-next-line vue/no-v-html -->
+								<span
+									class="text-sm [&_a]:text-info [&_a]:font-medium [&_a]:underline"
+									v-html="step"
+								/>
+							</li>
+						</ol>
+					</div>
+				</template>
+				<template v-else>
+					<div class="flex flex-col gap-1.5">
+						<h3 class="text-base font-bold m-0">Unknown error</h3>
+						<p class="text-sm text-secondary m-0">
+							We don’t recognize this error and can’t recommend specific steps to resolve it.
+						</p>
+						<p class="text-sm text-secondary m-0">
+							Try visiting
+							<a
+								class="text-info font-medium underline hover:underline"
+								href="https://www.minecraft.net/en-us/login"
+								>Minecraft Login</a
+							>
+							and signing in, as it may prompt you with the necessary steps. You can also contact
+							support and we can look into it further.
+						</p>
+					</div>
+				</template>
+			</div>
+
+			<!-- Action buttons -->
+			<div class="flex items-center gap-2">
+				<ButtonStyled>
+					<a href="https://support.modrinth.com" class="!w-full" @click="modal?.hide()">
+						<MessagesSquareIcon /> Contact support
+					</a>
+				</ButtonStyled>
+				<ButtonStyled color="brand">
+					<button :disabled="loadingSignIn" class="!w-full" @click="signInAgain">
+						<LogInIcon /> Sign in again
+					</button>
+				</ButtonStyled>
+			</div>
+
+			<div class="flex flex-col gap-2">
+				<div class="w-full h-[1px] bg-surface-5"></div>
+
+				<!-- Debug info -->
+				<div class="overflow-clip">
+					<button
+						class="flex items-center justify-between w-full bg-transparent border-0 py-4 cursor-pointer"
+						@click="debugCollapsed = !debugCollapsed"
+					>
+						<span class="flex items-center gap-2 text-contrast font-extrabold m-0">
+							<WrenchIcon class="h-4 w-4" />
+							Debug information
+						</span>
+						<DropdownIcon
+							class="h-5 w-5 text-secondary transition-transform"
+							:class="{ 'rotate-180': !debugCollapsed }"
+						/>
+					</button>
+					<Collapsible :collapsed="debugCollapsed">
+						<div class="p-3 bg-surface-2 rounded-2xl text-xs flex items-start">
+							<div class="m-0 p-0 rounded-none bg-transparent text-sm font-mono">
+								{{ debugInfo }}
+							</div>
+							<ButtonStyled circular>
+								<button
+									v-tooltip="'Copy debug info'"
+									:disabled="copied"
+									@click="copyToClipboard(debugInfo)"
+								>
+									<template v-if="copied"> <CheckIcon class="text-green" /> </template>
+									<template v-else> <CopyIcon /> </template>
+								</button>
+							</ButtonStyled>
+						</div>
+					</Collapsible>
+				</div>
+			</div>
+		</div>
+	</NewModal>
+</template>
diff --git a/apps/app-frontend/src/components/ui/minecraft-auth-error-modal/minecraft-auth-errors.ts b/apps/app-frontend/src/components/ui/minecraft-auth-error-modal/minecraft-auth-errors.ts
new file mode 100644
index 000000000..5e33d7aaa
--- /dev/null
+++ b/apps/app-frontend/src/components/ui/minecraft-auth-error-modal/minecraft-auth-errors.ts
@@ -0,0 +1,90 @@
+export interface MinecraftAuthError {
+	errorCode: string
+	whatHappened: string
+	stepsToFix: string[]
+}
+
+export const minecraftAuthErrors: MinecraftAuthError[] = [
+	{
+		errorCode: '2148916222',
+		whatHappened:
+			'Your Minecraft/Xbox Live account requires age verification to comply with UK regulations. You must complete this before signing in.',
+		stepsToFix: [
+			'Go to the <a href="https://www.minecraft.net/en-us/login">Minecraft Login</a> page and sign in',
+			'Follow the instructions to verify your age',
+			'Once verified, try signing in again',
+			'For additional help, visit <a href="https://support.xbox.com/en-GB/help/family-online-safety/online-safety/UK-age-verification">UK age verification on Xbox</a>',
+		],
+	},
+	{
+		errorCode: '2148916233',
+		whatHappened: "This account doesn't have an Xbox profile set up or doesn't own Minecraft.",
+		stepsToFix: [
+			'Make sure Minecraft is purchased on this account',
+			'Visit <a href="https://www.minecraft.net/en-us/login">Minecraft Login</a> and sign in',
+			'Complete Xbox profile setup if prompted',
+			'Once finished, try signing in again',
+		],
+	},
+	{
+		errorCode: '2148916235',
+		whatHappened: "Xbox Live isn't available in your region, so sign-in is blocked.",
+		stepsToFix: [
+			'Xbox services must be supported in your country before you can sign in',
+			'Check <a href="https://www.xbox.com/en-US/regions">Xbox Availability</a> for supported regions',
+		],
+	},
+	{
+		errorCode: '2148916236',
+		whatHappened: 'This account requires adult verification under South Korean regulations.',
+		stepsToFix: [
+			'Visit <a href="https://www.xbox.com">Xbox</a> and sign in',
+			'Complete the identity verification process',
+			'Once finished, try signing in again',
+		],
+	},
+	{
+		errorCode: '2148916237',
+		whatHappened: 'This account requires adult verification under South Korean regulations.',
+		stepsToFix: [
+			'Visit <a href="https://www.xbox.com">Xbox</a> and sign in',
+			'Complete the identity verification process',
+			'Once finished, try signing in again',
+		],
+	},
+	{
+		errorCode: '2148916238',
+		whatHappened: 'This account is underage and not linked to a Microsoft family group.',
+		stepsToFix: [
+			'Review the <a href="https://help.minecraft.net/hc/en-us/articles/4408968616077">Family Setup Guide</a>',
+			'Join or create a family group as instructed',
+			'Once finished, try signing in again',
+		],
+	},
+	{
+		errorCode: '2148916227',
+		whatHappened: 'This account was suspended for violating Xbox Community Standards.',
+		stepsToFix: [
+			'Visit <a href="https://support.xbox.com">Xbox Support</a> and review the enforcement details',
+			'Submit an appeal if one is available',
+		],
+	},
+	{
+		errorCode: '2148916229',
+		whatHappened: "This account is restricted and doesn't have permission to play online.",
+		stepsToFix: [
+			'Have a guardian sign in to <a href="https://account.microsoft.com/family/">Microsoft Family</a>',
+			'Update online play permissions',
+			'Once finished, try signing in again',
+		],
+	},
+	{
+		errorCode: '2148916234',
+		whatHappened: "This account hasn't accepted Xbox's Terms of Service.",
+		stepsToFix: [
+			'Visit <a href="https://www.xbox.com">Xbox</a> and sign in',
+			'Accept the Terms if prompted',
+			'Once finished, try signing in again',
+		],
+	},
+]
diff --git a/apps/app-frontend/src/store/error.js b/apps/app-frontend/src/store/error.js
index 0e7213fe5..dfec21120 100644
--- a/apps/app-frontend/src/store/error.js
+++ b/apps/app-frontend/src/store/error.js
@@ -3,12 +3,24 @@ import { defineStore } from 'pinia'
 export const useError = defineStore('errorsStore', {
 	state: () => ({
 		errorModal: null,
+		minecraftAuthErrorModal: null,
 	}),
 	actions: {
 		setErrorModal(ref) {
 			this.errorModal = ref
 		},
+		setMinecraftAuthErrorModal(ref) {
+			this.minecraftAuthErrorModal = ref
+		},
 		showError(error, context, closable = true, source = null) {
+			if (
+				error.message &&
+				error.message.includes('Minecraft authentication error:') &&
+				this.minecraftAuthErrorModal
+			) {
+				this.minecraftAuthErrorModal.show(error)
+				return
+			}
 			this.errorModal.show(error, context, closable, source)
 		},
 	},
diff --git a/packages/assets/generated-icons.ts b/packages/assets/generated-icons.ts
index 22569d9b3..cc0f353e2 100644
--- a/packages/assets/generated-icons.ts
+++ b/packages/assets/generated-icons.ts
@@ -144,6 +144,7 @@ import _ManageIcon from './icons/manage.svg?component'
 import _MaximizeIcon from './icons/maximize.svg?component'
 import _MemoryStickIcon from './icons/memory-stick.svg?component'
 import _MessageIcon from './icons/message.svg?component'
+import _MessagesSquareIcon from './icons/messages-square.svg?component'
 import _MicrophoneIcon from './icons/microphone.svg?component'
 import _MinimizeIcon from './icons/minimize.svg?component'
 import _MinusIcon from './icons/minus.svg?component'
@@ -466,6 +467,7 @@ export const ManageIcon = _ManageIcon
 export const MaximizeIcon = _MaximizeIcon
 export const MemoryStickIcon = _MemoryStickIcon
 export const MessageIcon = _MessageIcon
+export const MessagesSquareIcon = _MessagesSquareIcon
 export const MicrophoneIcon = _MicrophoneIcon
 export const MinimizeIcon = _MinimizeIcon
 export const MinusIcon = _MinusIcon
diff --git a/packages/assets/icons/messages-square.svg b/packages/assets/icons/messages-square.svg
new file mode 100644
index 000000000..68acfc88a
--- /dev/null
+++ b/packages/assets/icons/messages-square.svg
@@ -0,0 +1,16 @@
+<!-- @license lucide-static v0.562.0 - ISC -->
+<svg
+  class="lucide lucide-messages-square"
+  xmlns="http://www.w3.org/2000/svg"
+  width="24"
+  height="24"
+  viewBox="0 0 24 24"
+  fill="none"
+  stroke="currentColor"
+  stroke-width="2"
+  stroke-linecap="round"
+  stroke-linejoin="round"
+>
+  <path d="M16 10a2 2 0 0 1-2 2H6.828a2 2 0 0 0-1.414.586l-2.202 2.202A.71.71 0 0 1 2 14.286V4a2 2 0 0 1 2-2h10a2 2 0 0 1 2 2z" />
+  <path d="M20 9a2 2 0 0 1 2 2v10.286a.71.71 0 0 1-1.212.502l-2.202-2.202A2 2 0 0 0 17.172 19H10a2 2 0 0 1-2-2v-1" />
+</svg>