diff --git a/.changes/nextrelease/multipart-falsy-values.json b/.changes/nextrelease/multipart-falsy-values.json
new file mode 100644
index 0000000000..58d0cad1d5
--- /dev/null
+++ b/.changes/nextrelease/multipart-falsy-values.json
@@ -0,0 +1,7 @@
+[
+  {
+    "type": "bugfix",
+    "category": "Multipart",
+    "description": "Fixes bug in `AbstractUploadManager` where valid falsy values are excluded."
+  }
+]
diff --git a/src/Multipart/AbstractUploadManager.php b/src/Multipart/AbstractUploadManager.php
index adc356ede4..96848fd6ca 100644
--- a/src/Multipart/AbstractUploadManager.php
+++ b/src/Multipart/AbstractUploadManager.php
@@ -240,7 +240,7 @@ private function determineState(): UploadState
         $id = [$required['upload_id'] => null];
         unset($required['upload_id']);
         foreach ($required as $key => $param) {
-            if (!$this->config[$key]) {
+            if (!isset($this->config[$key]) || $this->config[$key] === '') {
                 throw new IAE('You must provide a value for "' . $key . '" in '
                     . 'your config for the MultipartUploader for '
                     . $this->client->getApi()->getServiceFullName() . '.');