diff --git a/app/assets/javascripts/discourse/app/lib/uppy-checksum-plugin.js b/app/assets/javascripts/discourse/app/lib/uppy-checksum-plugin.js
index ec73104541d..977a01659b2 100644
--- a/app/assets/javascripts/discourse/app/lib/uppy-checksum-plugin.js
+++ b/app/assets/javascripts/discourse/app/lib/uppy-checksum-plugin.js
@@ -1,5 +1,6 @@
 import { UploadPreProcessorPlugin } from "discourse/lib/uppy-plugin-base";
 import { Promise } from "rsvp";
+import { HUGE_FILE_THRESHOLD_BYTES } from "discourse/mixins/uppy-upload";
 
 export default class UppyChecksum extends UploadPreProcessorPlugin {
   static pluginId = "uppy-checksum";
@@ -34,14 +35,20 @@ export default class UppyChecksum extends UploadPreProcessorPlugin {
 
   _generateChecksum(fileIds) {
     if (!this._canUseSubtleCrypto()) {
-      return Promise.resolve();
+      return this._skipAll(fileIds, true);
     }
 
     let promises = fileIds.map((fileId) => {
       let file = this._getFile(fileId);
-
       this._emitProgress(file);
 
+      if (file.size > HUGE_FILE_THRESHOLD_BYTES) {
+        this._consoleWarn(
+          "The file provided is too large to checksum, skipping."
+        );
+        return this._skip(file);
+      }
+
       return file.data.arrayBuffer().then((arrayBuffer) => {
         return window.crypto.subtle
           .digest("SHA-1", arrayBuffer)
diff --git a/app/assets/javascripts/discourse/app/lib/uppy-media-optimization-plugin.js b/app/assets/javascripts/discourse/app/lib/uppy-media-optimization-plugin.js
index 4a00374468b..15ba5aa419b 100644
--- a/app/assets/javascripts/discourse/app/lib/uppy-media-optimization-plugin.js
+++ b/app/assets/javascripts/discourse/app/lib/uppy-media-optimization-plugin.js
@@ -22,17 +22,19 @@ export default class UppyMediaOptimization extends UploadPreProcessorPlugin {
 
     return this.optimizeFn(file, { stopWorkerOnError: !this.runParallel })
       .then((optimizedFile) => {
+        let skipped = false;
         if (!optimizedFile) {
           this._consoleWarn(
-            "Nothing happened, possible error or other restriction."
+            "Nothing happened, possible error or other restriction, or the file format is not a valid one for compression."
           );
+          skipped = true;
         } else {
           this._setFileState(fileId, {
             data: optimizedFile,
             size: optimizedFile.size,
           });
         }
-        this._emitComplete(file);
+        this._emitComplete(file, skipped);
       })
       .catch((err) => {
         this._consoleWarn(err);
diff --git a/app/assets/javascripts/discourse/app/lib/uppy-plugin-base.js b/app/assets/javascripts/discourse/app/lib/uppy-plugin-base.js
index 34eddeb050a..f7a0f871460 100644
--- a/app/assets/javascripts/discourse/app/lib/uppy-plugin-base.js
+++ b/app/assets/javascripts/discourse/app/lib/uppy-plugin-base.js
@@ -1,4 +1,5 @@
 import { BasePlugin } from "@uppy/core";
+import { Promise } from "rsvp";
 import { warn } from "@ember/debug";
 
 export class UppyPluginBase extends BasePlugin {
@@ -8,7 +9,14 @@ export class UppyPluginBase extends BasePlugin {
   }
 
   _consoleWarn(msg) {
-    warn(msg, { id: `discourse.${this.id}` });
+    warn(`[${this.id}] ${msg}`, { id: `discourse.${this.id}` });
+  }
+
+  _consoleDebug(msg) {
+    if (this.siteSettings?.enable_upload_debug_mode) {
+      // eslint-disable-next-line no-console
+      console.log(`[${this.id}] ${msg}`);
+    }
   }
 
   _getFile(fileId) {
@@ -41,10 +49,36 @@ export class UploadPreProcessorPlugin extends UppyPluginBase {
   }
 
   _emitProgress(file) {
-    this.uppy.emit("preprocess-progress", this.id, file);
+    this.uppy.emit("preprocess-progress", file, null, this.id);
   }
 
-  _emitComplete(file) {
-    this.uppy.emit("preprocess-complete", this.id, file);
+  _emitComplete(file, skipped = false) {
+    this.uppy.emit("preprocess-complete", file, skipped, this.id);
+    return Promise.resolve();
+  }
+
+  _emitAllComplete(fileIds, skipped = false) {
+    fileIds.forEach((fileId) => {
+      let file = this._getFile(fileId);
+      this._emitComplete(file, skipped);
+    });
+    return Promise.resolve();
+  }
+
+  _emitError(file, errorMessage) {
+    // the error message is stored twice; once to show in a displayErrorForUpload
+    // modal, and on the .message property to show in the uppy logs
+    this.uppy.emit("upload-error", file, {
+      errors: [errorMessage],
+      message: `[${this.id}] ${errorMessage}`,
+    });
+  }
+
+  _skip(file) {
+    return this._emitComplete(file, true);
+  }
+
+  _skipAll(file) {
+    return this._emitAllComplete(file, true);
   }
 }
diff --git a/app/assets/javascripts/discourse/app/mixins/composer-upload-uppy.js b/app/assets/javascripts/discourse/app/mixins/composer-upload-uppy.js
index 6bbbe659357..efbb0c75d1f 100644
--- a/app/assets/javascripts/discourse/app/mixins/composer-upload-uppy.js
+++ b/app/assets/javascripts/discourse/app/mixins/composer-upload-uppy.js
@@ -382,6 +382,8 @@ export default Mixin.create(ExtendableUploader, {
       limit: 10,
 
       createMultipartUpload(file) {
+        self._uppyInstance.emit("create-multipart", file.id);
+
         const data = {
           file_name: file.name,
           file_size: file.size,
@@ -402,6 +404,8 @@ export default Mixin.create(ExtendableUploader, {
           data,
           // uppy is inconsistent, an error here fires the upload-error event
         }).then((responseData) => {
+          self._uppyInstance.emit("create-multipart-success", file.id);
+
           file.meta.unique_identifier = responseData.unique_identifier;
           return {
             uploadId: responseData.external_upload_identifier,
@@ -430,6 +434,7 @@ export default Mixin.create(ExtendableUploader, {
       },
 
       completeMultipartUpload(file, data) {
+        self._uppyInstance.emit("complete-multipart", file.id);
         const parts = data.parts.map((part) => {
           return { part_number: part.PartNumber, etag: part.ETag };
         });
@@ -442,6 +447,7 @@ export default Mixin.create(ExtendableUploader, {
           }),
           // uppy is inconsistent, an error here fires the upload-error event
         }).then((responseData) => {
+          self._uppyInstance.emit("complete-multipart-success", file.id);
           return responseData;
         });
       },
@@ -556,11 +562,4 @@ export default Mixin.create(ExtendableUploader, {
   showUploadSelector(toolbarEvent) {
     this.send("showUploadSelector", toolbarEvent);
   },
-
-  _debugLog(message) {
-    if (this.siteSettings.enable_upload_debug_mode) {
-      // eslint-disable-next-line no-console
-      console.log(message);
-    }
-  },
 });
diff --git a/app/assets/javascripts/discourse/app/mixins/extendable-uploader.js b/app/assets/javascripts/discourse/app/mixins/extendable-uploader.js
index 120abb13ad8..4c12f7ac80c 100644
--- a/app/assets/javascripts/discourse/app/mixins/extendable-uploader.js
+++ b/app/assets/javascripts/discourse/app/mixins/extendable-uploader.js
@@ -80,8 +80,10 @@ export default Mixin.create({
   //
   // See: https://uppy.io/docs/writing-plugins/#Progress-events
   _onPreProcessProgress(callback) {
-    this._uppyInstance.on("preprocess-progress", (pluginId, file) => {
-      this._debugLog(`[${pluginId}] processing file ${file.name} (${file.id})`);
+    this._uppyInstance.on("preprocess-progress", (file, progress, pluginId) => {
+      this._consoleDebug(
+        `[${pluginId}] processing file ${file.name} (${file.id})`
+      );
 
       this._preProcessorStatus[pluginId].activeProcessing++;
 
@@ -90,16 +92,18 @@ export default Mixin.create({
   },
 
   _onPreProcessComplete(callback, allCompleteCallback) {
-    this._uppyInstance.on("preprocess-complete", (pluginId, file) => {
-      this._debugLog(
-        `[${pluginId}] completed processing file ${file.name} (${file.id})`
+    this._uppyInstance.on("preprocess-complete", (file, skipped, pluginId) => {
+      this._consoleDebug(
+        `[${pluginId}] ${skipped ? "skipped" : "completed"} processing file ${
+          file.name
+        } (${file.id})`
       );
 
       callback(file);
 
       this._completePreProcessing(pluginId, (allComplete) => {
         if (allComplete) {
-          this._debugLog("All upload preprocessors complete.");
+          this._consoleDebug("[uppy] All upload preprocessors complete!");
           allCompleteCallback();
         }
       });
@@ -168,4 +172,11 @@ export default Mixin.create({
       }
     }
   },
+
+  _consoleDebug(msg) {
+    if (this.siteSettings.enable_upload_debug_mode) {
+      // eslint-disable-next-line no-console
+      console.log(msg);
+    }
+  },
 });
diff --git a/app/assets/javascripts/discourse/app/mixins/uppy-upload.js b/app/assets/javascripts/discourse/app/mixins/uppy-upload.js
index 5c9cbb8aeb9..ad8cd44084a 100644
--- a/app/assets/javascripts/discourse/app/mixins/uppy-upload.js
+++ b/app/assets/javascripts/discourse/app/mixins/uppy-upload.js
@@ -16,6 +16,8 @@ import UppyChecksum from "discourse/lib/uppy-checksum-plugin";
 import { on } from "discourse-common/utils/decorators";
 import { warn } from "@ember/debug";
 
+export const HUGE_FILE_THRESHOLD_BYTES = 104_857_600; // 100MB
+
 export default Mixin.create({
   uploading: false,
   uploadProgress: 0,
diff --git a/app/assets/javascripts/discourse/tests/unit/lib/uppy-checksum-plugin-test.js b/app/assets/javascripts/discourse/tests/unit/lib/uppy-checksum-plugin-test.js
index ae0c6fbeba4..58cd1b7e276 100644
--- a/app/assets/javascripts/discourse/tests/unit/lib/uppy-checksum-plugin-test.js
+++ b/app/assets/javascripts/discourse/tests/unit/lib/uppy-checksum-plugin-test.js
@@ -10,10 +10,17 @@ class FakeUppy {
       "uppy-test/file/vv2/xvejg5w/blah/png-1d-1d-2v-1d-1e-image/jpeg-9043429-1624921727764": {
         meta: {},
         data: createFile("test1.png"),
+        size: 1024,
       },
       "uppy-test/file/blah1/ads37x2/blah1/png-1d-1d-2v-1d-1e-image/jpeg-99999-1837921727764": {
         meta: {},
         data: createFile("test2.png"),
+        size: 2048,
+      },
+      "uppy-test/file/mnb3/jfhrg43x/blah3/png-1d-1d-2v-1d-1e-image/jpeg-111111-1837921727764": {
+        meta: {},
+        data: createFile("test2.png"),
+        size: 209715200,
       },
     };
   }
@@ -62,8 +69,8 @@ module("Unit | Utility | UppyChecksum Plugin", function () {
     plugin.uppy.preprocessors[0]([fileId]).then(() => {
       assert.equal(
         plugin.uppy.emitted.length,
-        0,
-        "no events were fired by the checksum plugin because it returned early"
+        1,
+        "only the complete event was fired by the checksum plugin because it skipped the file"
       );
       done();
     });
@@ -85,8 +92,8 @@ module("Unit | Utility | UppyChecksum Plugin", function () {
     plugin.uppy.preprocessors[0]([fileId]).then(() => {
       assert.equal(
         plugin.uppy.emitted.length,
-        0,
-        "no events were fired by the checksum plugin because it returned early"
+        1,
+        "only the complete event was fired by the checksum plugin because it skipped the file"
       );
       done();
     });
@@ -106,13 +113,32 @@ module("Unit | Utility | UppyChecksum Plugin", function () {
     plugin.uppy.preprocessors[0]([fileId]).then(() => {
       assert.equal(
         plugin.uppy.emitted.length,
-        0,
-        "no events were fired by the checksum plugin because it returned early"
+        1,
+        "only the complete event was fired by the checksum plugin because it skipped the file"
       );
       done();
     });
   });
 
+  test("it does nothing if the file is > 100MB", function (assert) {
+    const capabilities = {};
+    const fakeUppy = new FakeUppy();
+    const plugin = new UppyChecksum(fakeUppy, {
+      capabilities,
+    });
+    plugin.install();
+    const done = assert.async();
+
+    const fileId =
+      "uppy-test/file/mnb3/jfhrg43x/blah3/png-1d-1d-2v-1d-1e-image/jpeg-111111-1837921727764";
+    plugin.uppy.preprocessors[0]([fileId]).then(() => {
+      assert.equal(plugin.uppy.emitted[0].event, "preprocess-progress");
+      assert.equal(plugin.uppy.emitted[1].event, "preprocess-complete");
+      assert.equal(plugin.uppy.getFile(fileId).meta.sha1_checksum, null);
+      done();
+    });
+  });
+
   test("it gets a sha1 hash of each file and adds it to the file meta", function (assert) {
     const capabilities = {};
     const fakeUppy = new FakeUppy();