diff --git a/public/js/extensions.js b/public/js/extensions.js
index 8b16e2b6..7549919d 100644
--- a/public/js/extensions.js
+++ b/public/js/extensions.js
@@ -196,3 +196,9 @@ function QrCodeImgHtml(text)
 
 	return img.outerHTML;
 }
+
+function CleanFileName(fileName)
+{
+	// Umlaute seem to cause problems on Linux...
+	return fileName.toLowerCase().replaceAll(/ä/g, 'ae').replaceAll(/ö/g, 'oe').replaceAll(/ü/g, 'ue').replaceAll(/ß/g, 'ss');
+}
diff --git a/public/viewjs/components/userfieldsform.js b/public/viewjs/components/userfieldsform.js
index 655fbca6..eca3f2d0 100644
--- a/public/viewjs/components/userfieldsform.js
+++ b/public/viewjs/components/userfieldsform.js
@@ -44,9 +44,9 @@ Grocy.Components.UserfieldsForm.Save = function(success, error)
 			if (input[0].files.length > 0)
 			{
 				// Files service requires an extension
-				var fileName = RandomString() + '.' + input[0].files[0].name.split('.').reverse()[0];
+				var fileName = RandomString() + '.' + CleanFileName(input[0].files[0].name.split('.').reverse()[0]);
 
-				jsonData[fieldName] = btoa(fileName) + '_' + btoa(input[0].files[0].name);
+				jsonData[fieldName] = btoa(fileName) + '_' + btoa(CleanFileName(input[0].files[0].name));
 				Grocy.Api.UploadFile(input[0].files[0], 'userfiles', fileName,
 					function(result)
 					{
diff --git a/public/viewjs/equipmentform.js b/public/viewjs/equipmentform.js
index 3cc44439..b42c3e79 100644
--- a/public/viewjs/equipmentform.js
+++ b/public/viewjs/equipmentform.js
@@ -13,7 +13,7 @@
 	if ($("#instruction-manual")[0].files.length > 0)
 	{
 		var someRandomStuff = RandomString();
-		jsonData.instruction_manual_file_name = someRandomStuff + $("#instruction-manual")[0].files[0].name;
+		jsonData.instruction_manual_file_name = someRandomStuff + CleanFileName($("#instruction-manual")[0].files[0].name);
 	}
 
 	if (Grocy.DeleteInstructionManualOnSave)
diff --git a/public/viewjs/productform.js b/public/viewjs/productform.js
index 88a8051e..bc9debb8 100644
--- a/public/viewjs/productform.js
+++ b/public/viewjs/productform.js
@@ -96,7 +96,7 @@ $('.save-product-button').on('click', function(e)
 	if ($("#product-picture")[0].files.length > 0)
 	{
 		var someRandomStuff = Math.random().toString(36).substring(2, 100) + Math.random().toString(36).substring(2, 100);
-		jsonData.picture_file_name = someRandomStuff + $("#product-picture")[0].files[0].name;
+		jsonData.picture_file_name = someRandomStuff + CleanFileName($("#product-picture")[0].files[0].name);
 	}
 
 	const location = $(e.currentTarget).attr('data-location') == 'return' ? '/products?product=' : '/product/';
diff --git a/public/viewjs/recipeform.js b/public/viewjs/recipeform.js
index a9a987c8..6237ee9a 100644
--- a/public/viewjs/recipeform.js
+++ b/public/viewjs/recipeform.js
@@ -36,7 +36,7 @@ $('.save-recipe').on('click', function(e)
 	if ($("#recipe-picture")[0].files.length > 0)
 	{
 		var someRandomStuff = Math.random().toString(36).substring(2, 100) + Math.random().toString(36).substring(2, 100);
-		jsonData.picture_file_name = someRandomStuff + $("#recipe-picture")[0].files[0].name;
+		jsonData.picture_file_name = someRandomStuff + CleanFileName($("#recipe-picture")[0].files[0].name);
 	}
 
 	const location = $(e.currentTarget).attr('data-location') == 'return' ? '/recipes?recipe=' : '/recipe/';
diff --git a/public/viewjs/userform.js b/public/viewjs/userform.js
index e55ffd44..ce348650 100644
--- a/public/viewjs/userform.js
+++ b/public/viewjs/userform.js
@@ -39,7 +39,7 @@ $('#save-user-button').on('click', function(e)
 	if ($("#user-picture")[0].files.length > 0)
 	{
 		var someRandomStuff = Math.random().toString(36).substring(2, 100) + Math.random().toString(36).substring(2, 100);
-		jsonData.picture_file_name = someRandomStuff + $("#user-picture")[0].files[0].name;
+		jsonData.picture_file_name = someRandomStuff + CleanFileName($("#user-picture")[0].files[0].name);
 	}
 
 	if (Grocy.EditMode === 'create')