diff --git a/CHANGELOG.md b/CHANGELOG.md
index 162d25cdf..398b0ee45 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -39,6 +39,12 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - our litepub JSON-LD schema is now served with the correct content type
 - remote APNG attachments are now recognised as images
 
+## Upgrade Notes
+
+- As mentioned in "Changed", `Pleroma.Upload, :base_url` **MUST** be configured. Uploads will fail without it.
+  - Akkoma will refuse to start if this is not set.
+- Same with media proxy.
+
 ## 2024.02
 
 ## Added
diff --git a/config/description.exs b/config/description.exs
index 3ddd874f8..ec5050be6 100644
--- a/config/description.exs
+++ b/config/description.exs
@@ -100,9 +100,9 @@ config :pleroma, :config_description, [
         label: "Base URL",
         type: :string,
         description:
-          "Base URL for the uploads. Required if you use a CDN or host attachments under a different domain.",
+          "Base URL for the uploads. Required if you use a CDN or host attachments under a different domain - it is HIGHLY recommended that you **do not** set this to be the same as the domain akkoma is hosted on.",
         suggestions: [
-          "https://cdn-host.com"
+          "https://media.akkoma.dev/media/"
         ]
       },
       %{
diff --git a/config/test.exs b/config/test.exs
index 666a0fb87..97d005eab 100644
--- a/config/test.exs
+++ b/config/test.exs
@@ -22,6 +22,7 @@ config :logger, :console,
 config :pleroma, :auth, oauth_consumer_strategies: []
 
 config :pleroma, Pleroma.Upload,
+  base_url: "http://localhost:4001/media/",
   filters: [],
   link_name: false
 
diff --git a/docs/docs/configuration/cheatsheet.md b/docs/docs/configuration/cheatsheet.md
index c4259c6cf..d238d73aa 100644
--- a/docs/docs/configuration/cheatsheet.md
+++ b/docs/docs/configuration/cheatsheet.md
@@ -602,7 +602,7 @@ the source code is here: [kocaptcha](https://github.com/koto-bank/kocaptcha). Th
 * `filters`: List of [upload filters](#upload-filters) to use.
 * `link_name`: When enabled Akkoma will add a `name` parameter to the url of the upload, for example `https://instance.tld/media/corndog.png?name=corndog.png`. This is needed to provide the correct filename in Content-Disposition headers
 * `base_url`: The base URL to access a user-uploaded file; MUST be configured explicitly.
-  Using a (sub)domain distinct from the instance endpoint is **strongly** recommended.
+  Using a (sub)domain distinct from the instance endpoint is **strongly** recommended. A good value might be `https://media.myakkoma.instance/media/`. 
 * `proxy_remote`: If you're using a remote uploader, Akkoma will proxy media requests instead of redirecting to it.
 * `proxy_opts`: Proxy options, see `Pleroma.ReverseProxy` documentation.
 * `filename_display_max_length`: Set max length of a filename to display. 0 = no limit. Default: 30.
diff --git a/lib/pleroma/config/deprecation_warnings.ex b/lib/pleroma/config/deprecation_warnings.ex
index beb3f5e7f..c299a4947 100644
--- a/lib/pleroma/config/deprecation_warnings.ex
+++ b/lib/pleroma/config/deprecation_warnings.ex
@@ -182,7 +182,9 @@ defmodule Pleroma.Config.DeprecationWarnings do
       check_quarantined_instances_tuples(),
       check_transparency_exclusions_tuples(),
       check_simple_policy_tuples(),
-      check_http_adapter()
+      check_http_adapter(),
+      check_uploader_base_url_set(),
+      check_uploader_base_url_is_not_base_domain()
     ]
     |> Enum.reduce(:ok, fn
       :ok, :ok -> :ok
@@ -337,4 +339,54 @@ defmodule Pleroma.Config.DeprecationWarnings do
       :ok
     end
   end
+
+  def check_uploader_base_url_set() do
+    uses_local_uploader? = Config.get([Pleroma.Upload, :uploader]) == Pleroma.Uploaders.Local
+    base_url = Pleroma.Config.get([Pleroma.Upload, :base_url])
+
+    if base_url || !uses_local_uploader? do
+      :ok
+    else
+      Logger.error("""
+      !!!WARNING!!!
+      Your config does not specify a base_url for uploads!
+      Please make the following change:\n
+      \n* `config :pleroma, Pleroma.Upload, base_url: "https://example.com/media/`
+      \n
+      \nPlease note that it is HEAVILY recommended to use a subdomain to host user-uploaded media!
+      """)
+
+      # This is a hard exit - the uploader will not work without a base_url
+      raise ArgumentError, message: "No base_url set for uploads - please set one in your config!"
+    end
+  end
+
+  def check_uploader_base_url_is_not_base_domain() do
+    uses_local_uploader? = Config.get([Pleroma.Upload, :uploader]) == Pleroma.Uploaders.Local
+
+    uploader_host =
+      [Pleroma.Upload, :base_url]
+      |> Pleroma.Config.get()
+      |> URI.parse()
+      |> Map.get(:host)
+
+    akkoma_host =
+      [Pleroma.Web.Endpoint, :url]
+      |> Pleroma.Config.get()
+      |> Keyword.get(:host)
+
+    if uploader_host == akkoma_host && uses_local_uploader? do
+      Logger.error("""
+      !!!WARNING!!!
+      Your Akkoma Host and your Upload base_url's host are the same!
+      This can potentially be insecure!
+
+      It is HIGHLY recommended that you migrate your media uploads
+      to a subdomain at your earliest convenience
+      """)
+    end
+
+    # This isn't actually an error condition, just a warning
+    :ok
+  end
 end
diff --git a/mix.exs b/mix.exs
index f501eec58..b942c6c23 100644
--- a/mix.exs
+++ b/mix.exs
@@ -4,7 +4,7 @@ defmodule Pleroma.Mixfile do
   def project do
     [
       app: :pleroma,
-      version: version("3.12.0"),
+      version: version("3.12.2"),
       elixir: "~> 1.14",
       elixirc_paths: elixirc_paths(Mix.env()),
       compilers: Mix.compilers(),
diff --git a/test/pleroma/config/deprecation_warnings_test.exs b/test/pleroma/config/deprecation_warnings_test.exs
index 98c128e6a..96d6fd739 100644
--- a/test/pleroma/config/deprecation_warnings_test.exs
+++ b/test/pleroma/config/deprecation_warnings_test.exs
@@ -289,4 +289,64 @@ defmodule Pleroma.Config.DeprecationWarningsTest do
 
     Application.put_env(:tesla, :adapter, Tesla.Mock)
   end
+
+  describe "check_uploader_base_url_set/0" do
+    test "should error if the base_url is not set" do
+      clear_config([Pleroma.Upload, :base_url], nil)
+
+      # we need to capture the error
+      assert_raise ArgumentError, fn ->
+        assert capture_log(fn ->
+                 DeprecationWarnings.check_uploader_base_url_set()
+               end) =~ "Your config does not specify a base_url for uploads!"
+      end
+    end
+
+    test "should not error if the base_url is set" do
+      clear_config([Pleroma.Upload, :base_url], "https://example.com")
+
+      refute capture_log(fn ->
+               DeprecationWarnings.check_uploader_base_url_set()
+             end) =~ "Your config does not specify a base_url for uploads!"
+    end
+
+    test "should not error if local uploader is not used" do
+      clear_config([Pleroma.Upload, :base_url], nil)
+      clear_config([Pleroma.Upload, :uploader], Pleroma.Uploaders.S3)
+
+      refute capture_log(fn ->
+               DeprecationWarnings.check_uploader_base_url_set()
+             end) =~ "Your config does not specify a base_url for uploads!"
+    end
+  end
+
+  describe "check_uploader_base_url_is_not_base_domain/0" do
+    test "should error if the akkoma domain is the same as the upload domain" do
+      clear_config([Pleroma.Upload, :base_url], "http://localhost")
+
+      assert capture_log(fn ->
+               DeprecationWarnings.check_uploader_base_url_is_not_base_domain()
+             end) =~ "Your Akkoma Host and your Upload base_url's host are the same!"
+    end
+
+    test "should not error if the local uploader is not used" do
+      clear_config([Pleroma.Upload, :base_url], "http://localhost")
+      clear_config([Pleroma.Upload, :uploader], Pleroma.Uploaders.S3)
+
+      refute capture_log(fn ->
+               DeprecationWarnings.check_uploader_base_url_is_not_base_domain()
+             end) =~ "Your Akkoma Host and your Upload base_url's host are the same!"
+    end
+
+    test "should not error if the akkoma domain is different from the upload domain" do
+      clear_config([Pleroma.Upload, :base_url], "https://media.localhost")
+      clear_config([Pleroma.Upload, :uploader], Pleroma.Uploaders.Local)
+
+      refute capture_log(fn ->
+               DeprecationWarnings.check_uploader_base_url_is_not_base_domain()
+             end) =~ "Your Akkoma Host and your Upload base_url's host are the same!"
+
+      clear_config([Pleroma.Upload, :base_url])
+    end
+  end
 end
diff --git a/test/pleroma/web/activity_pub/mrf/steal_emoji_policy_test.exs b/test/pleroma/web/activity_pub/mrf/steal_emoji_policy_test.exs
index ba5087f1b..932251389 100644
--- a/test/pleroma/web/activity_pub/mrf/steal_emoji_policy_test.exs
+++ b/test/pleroma/web/activity_pub/mrf/steal_emoji_policy_test.exs
@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: AGPL-3.0-only
 
 defmodule Pleroma.Web.ActivityPub.MRF.StealEmojiPolicyTest do
-  use Pleroma.DataCase
+  use Pleroma.DataCase, async: false
 
   alias Pleroma.Config
   alias Pleroma.Emoji
@@ -60,6 +60,9 @@ defmodule Pleroma.Web.ActivityPub.MRF.StealEmojiPolicyTest do
 
     emoji_path = [:instance, :static_dir] |> Config.get() |> Path.join("emoji/stolen")
 
+    emoji_base_path = [:instance, :static_dir] |> Config.get() |> Path.join("emoji/")
+    File.mkdir_p(emoji_base_path)
+
     Emoji.reload()
 
     message = %{
diff --git a/test/pleroma/web/plugs/http_security_plug_test.exs b/test/pleroma/web/plugs/http_security_plug_test.exs
index 3c029b9b2..bd8207ae0 100644
--- a/test/pleroma/web/plugs/http_security_plug_test.exs
+++ b/test/pleroma/web/plugs/http_security_plug_test.exs
@@ -7,6 +7,8 @@ defmodule Pleroma.Web.Plugs.HTTPSecurityPlugTest do
 
   alias Plug.Conn
 
+  setup_all do: clear_config([Pleroma.Upload, :base_url], nil)
+
   describe "http security enabled" do
     setup do: clear_config([:http_security, :enabled], true)