diff --git a/apps/workflowengine/src/components/Checks/FileMimeType.vue b/apps/workflowengine/src/components/Checks/FileMimeType.vue
index 2f2487c9adf..862c4a42011 100644
--- a/apps/workflowengine/src/components/Checks/FileMimeType.vue
+++ b/apps/workflowengine/src/components/Checks/FileMimeType.vue
@@ -32,17 +32,20 @@
 			:tagging="false"
 			@input="setValue">
 			<template slot="singleLabel" slot-scope="props">
-				<span class="option__icon" :class="props.option.icon" />
+				<span v-if="props.option.icon" class="option__icon" :class="props.option.icon" />
+				<img v-else :src="props.option.iconUrl" />
 				<span class="option__title option__title_single">{{ props.option.label }}</span>
 			</template>
 			<template slot="option" slot-scope="props">
-				<span class="option__icon" :class="props.option.icon" />
+				<span v-if="props.option.icon" class="option__icon" :class="props.option.icon" />
+				<img v-else :src="props.option.iconUrl" />
 				<span class="option__title">{{ props.option.label }}</span>
 			</template>
 		</Multiselect>
 		<input v-if="!isPredefined"
 			type="text"
 			:value="currentValue.pattern"
+			:placeholder="t('workflowengine', 'e.g. httpd/unix-directory')"
 			@input="updateCustom">
 	</div>
 </template>
@@ -68,12 +71,12 @@ export default {
 					pattern: '/image\\/.*/'
 				},
 				{
-					icon: 'icon-category-office',
+					iconUrl: OC.imagePath('core', 'filetypes/x-office-document'),
 					label: t('workflowengine', 'Office documents'),
 					pattern: '/(vnd\\.(ms-|openxmlformats-).*))$/'
 				},
 				{
-					icon: 'icon-filetype-file',
+					iconUrl: OC.imagePath('core', 'filetypes/application-pdf'),
 					label: t('workflowengine', 'PDF documents'),
 					pattern: 'application/pdf'
 				}
@@ -130,3 +133,15 @@ export default {
 	}
 }
 </script>
+<style scoped>
+	.multiselect, input[type='text'] {
+		width: 100%;
+	}
+	.multiselect >>> .multiselect__content-wrapper li>span,
+	.multiselect >>> .multiselect__single {
+		display: flex;
+		white-space: nowrap;
+		overflow: hidden;
+		text-overflow: ellipsis;
+	}
+</style>
diff --git a/apps/workflowengine/src/components/Checks/RequestTime.vue b/apps/workflowengine/src/components/Checks/RequestTime.vue
index 1d7950f64f8..cd702ecae82 100644
--- a/apps/workflowengine/src/components/Checks/RequestTime.vue
+++ b/apps/workflowengine/src/components/Checks/RequestTime.vue
@@ -4,12 +4,13 @@
 		<input v-model="newValue.startTime"
 			type="text"
 			class="timeslot--start"
-			placeholder="08:00"
+			placeholder="e.g. 08:00"
 			@input="update">
 		<input v-model="newValue.endTime"
 			type="text"
-			placeholder="18:00"
+			placeholder="e.g. 18:00"
 			@input="update">
+		<p v-if="!valid" class="invalid-hint">{{ t('workflowengine', 'Please enter a valid time span')}}</p>
 	</div>
 </template>
 
@@ -30,7 +31,7 @@ export default {
 	props: {
 		value: {
 			type: String,
-			default: '1 MB'
+			default: ''
 		}
 	},
 	data() {
@@ -46,15 +47,16 @@ export default {
 	},
 	methods: {
 		updateInternalValue(value) {
-			var data = JSON.parse(value)
-			var startTime = data[0].split(' ', 2)[0]
-			var endTime = data[1].split(' ', 2)[0]
-			var timezone = data[0].split(' ', 2)[1]
-			this.newValue = {
-				startTime: startTime,
-				endTime: endTime,
-				timezone: timezone
-			}
+			try {
+				const data = JSON.parse(value)
+				if (data.length === 2) {
+					this.newValue = {
+						startTime: data[0].split(' ', 2)[0],
+						endTime: data[1].split(' ', 2)[0],
+						timezone: data[0].split(' ', 2)[1]
+					}
+				}
+			} catch (e) {}
 		},
 		validate() {
 			return this.newValue.startTime && this.newValue.startTime.match(/^(0[0-9]|1[0-9]|2[0-3]|[0-9]):[0-5][0-9]$/i) !== null
@@ -90,10 +92,15 @@ export default {
 			width: 50%;
 			margin: 0;
 			margin-bottom: 5px;
+
 			&.timeslot--start {
 				margin-right: 5px;
 				width: calc(50% - 5px);
 			}
 		}
+
+		.invalid-hint {
+			color: var(--color-text-maxcontrast);
+		}
 	}
 </style>
diff --git a/apps/workflowengine/src/components/Checks/file.js b/apps/workflowengine/src/components/Checks/file.js
index 76f998da007..0cc49c2d4c1 100644
--- a/apps/workflowengine/src/components/Checks/file.js
+++ b/apps/workflowengine/src/components/Checks/file.js
@@ -65,7 +65,7 @@ const FileChecks = [
 			{ operator: 'greater', name: t('workflowengine', 'greater') }
 		],
 		placeholder: (check) => '5 MB',
-		validate: (check) => check.value.match(/^[0-9]+[ ]?[kmgt]?b$/i) !== null
+		validate: (check) => check.value ? check.value.match(/^[0-9]+[ ]?[kmgt]?b$/i) !== null : false
 	},
 
 	{
diff --git a/apps/workflowengine/src/helpers/validators.js b/apps/workflowengine/src/helpers/validators.js
index 837b20ad44c..4936b9200f7 100644
--- a/apps/workflowengine/src/helpers/validators.js
+++ b/apps/workflowengine/src/helpers/validators.js
@@ -24,16 +24,25 @@ const regexIPv4 = /^(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.(25[0-5]|2[0-4][0-9]
 const regexIPv6 = /^(([0-9a-fA-F]{1,4}:){7,7}[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,7}:|([0-9a-fA-F]{1,4}:){1,6}:[0-9a-fA-F]{1,4}|([0-9a-fA-F]{1,4}:){1,5}(:[0-9a-fA-F]{1,4}){1,2}|([0-9a-fA-F]{1,4}:){1,4}(:[0-9a-fA-F]{1,4}){1,3}|([0-9a-fA-F]{1,4}:){1,3}(:[0-9a-fA-F]{1,4}){1,4}|([0-9a-fA-F]{1,4}:){1,2}(:[0-9a-fA-F]{1,4}){1,5}|[0-9a-fA-F]{1,4}:((:[0-9a-fA-F]{1,4}){1,6})|:((:[0-9a-fA-F]{1,4}){1,7}|:)|fe80:(:[0-9a-fA-F]{0,4}){0,4}%[0-9a-zA-Z]{1,}|::(ffff(:0{1,4}){0,1}:){0,1}((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])|([0-9a-fA-F]{1,4}:){1,4}:((25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9])\.){3,3}(25[0-5]|(2[0-4]|1{0,1}[0-9]){0,1}[0-9]))\/(1([01][0-9]|2[0-8])|[1-9][0-9]|[0-9])$/
 
 const validateRegex = function(string) {
+	if (!string) {
+		return false
+	}
 	const result = regexRegex.exec(string)
 	return result !== null
 }
 
 const validateIPv4 = function(string) {
+	if (!string) {
+		return false
+	}
 	const result = regexIPv4.exec(string)
 	return result !== null
 }
 
 const validateIPv6 = function(string) {
+	if (!string) {
+		return false
+	}
 	const result = regexIPv6.exec(string)
 	return result !== null
 }