diff --git a/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/Timezones.tsx b/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/Timezones.tsx
index 8d012dedb..268eed76f 100644
--- a/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/Timezones.tsx
+++ b/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/Timezones.tsx
@@ -1,15 +1,15 @@
 import React, { FC, useMemo, useRef, useState } from "preact/compat";
-import { getTimezoneList, getUTCByTimezone } from "../../../../utils/time";
+import { getBrowserTimezone, getTimezoneList, getUTCByTimezone } from "../../../../utils/time";
 import { ArrowDropDownIcon } from "../../../Main/Icons";
 import classNames from "classnames";
 import Popper from "../../../Main/Popper/Popper";
 import Accordion from "../../../Main/Accordion/Accordion";
-import dayjs from "dayjs";
 import TextField from "../../../Main/TextField/TextField";
 import { Timezone } from "../../../../types";
 import "./style.scss";
 import useDeviceDetect from "../../../../hooks/useDeviceDetect";
 import useBoolean from "../../../../hooks/useBoolean";
+import WarningTimezone from "./WarningTimezone";
 
 interface TimezonesProps {
   timezoneState: string;
@@ -18,9 +18,12 @@ interface TimezonesProps {
 }
 
 interface PinnedTimezone extends Timezone {
-  title: string
+  title: string;
+  isInvalid?: boolean;
 }
 
+const browserTimezone = getBrowserTimezone();
+
 const Timezones: FC<TimezonesProps> = ({ timezoneState, defaultTimezone, onChange }) => {
   const { isMobile } = useDeviceDetect();
   const timezones = getTimezoneList();
@@ -41,9 +44,10 @@ const Timezones: FC<TimezonesProps> = ({ timezoneState, defaultTimezone, onChang
       utc: defaultTimezone ? getUTCByTimezone(defaultTimezone) : "UTC"
     },
     {
-      title: `Browser Time (${dayjs.tz.guess()})`,
-      region: dayjs.tz.guess(),
-      utc: getUTCByTimezone(dayjs.tz.guess())
+      title: browserTimezone.title,
+      region: browserTimezone.region,
+      utc: getUTCByTimezone(browserTimezone.region),
+      isInvalid: !browserTimezone.isValid
     },
     {
       title: "UTC (Coordinated Universal Time)",
@@ -132,7 +136,7 @@ const Timezones: FC<TimezonesProps> = ({ timezoneState, defaultTimezone, onChang
                 className="vm-timezones-item vm-timezones-list-group-options__item"
                 onClick={createHandlerSetTimezone(t)}
               >
-                <div className="vm-timezones-item__title">{t.title}</div>
+                <div className="vm-timezones-item__title">{t.title}{t.isInvalid && <WarningTimezone/>}</div>
                 <div className="vm-timezones-item__utc">{t.utc}</div>
               </div>
             ))}
diff --git a/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/WarningTimezone.tsx b/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/WarningTimezone.tsx
new file mode 100644
index 000000000..8231c5f7f
--- /dev/null
+++ b/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/WarningTimezone.tsx
@@ -0,0 +1,16 @@
+import React, { FC } from "preact/compat";
+import Tooltip from "../../../Main/Tooltip/Tooltip";
+import { WarningIcon } from "../../../Main/Icons";
+
+const waringText = "Browser timezone is not recognized, supported, or could not be determined.";
+
+const WarningTimezone: FC = () => {
+
+  return (
+    <Tooltip title={waringText}>
+      <WarningIcon/>
+    </Tooltip>
+  );
+};
+
+export default WarningTimezone;
diff --git a/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/style.scss b/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/style.scss
index 512f24db3..506e5d87b 100644
--- a/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/style.scss
+++ b/app/vmui/packages/vmui/src/components/Configurators/GlobalSettings/Timezones/style.scss
@@ -16,7 +16,15 @@
     }
 
     &__title {
+      display: flex;
+      align-items: center;
+      gap: $padding-small;
       text-transform: capitalize;
+
+      svg {
+        width: 14px;
+        color: $color-warning;
+      }
     }
 
     &__utc {
diff --git a/app/vmui/packages/vmui/src/hooks/useFetchDefaultTimezone.ts b/app/vmui/packages/vmui/src/hooks/useFetchDefaultTimezone.ts
index b2460a1d0..ed59a6ab8 100644
--- a/app/vmui/packages/vmui/src/hooks/useFetchDefaultTimezone.ts
+++ b/app/vmui/packages/vmui/src/hooks/useFetchDefaultTimezone.ts
@@ -4,6 +4,7 @@ import { useAppState } from "../state/common/StateContext";
 import { useTimeDispatch } from "../state/time/TimeStateContext";
 import { getFromStorage } from "../utils/storage";
 import dayjs from "dayjs";
+import { getBrowserTimezone } from "../utils/time";
 
 const disabledDefaultTimezone = Boolean(getFromStorage("DISABLED_DEFAULT_TIMEZONE"));
 
@@ -15,7 +16,7 @@ const useFetchDefaultTimezone = () => {
   const [error, setError] = useState<ErrorTypes | string>("");
 
   const setTimezone = (timezoneStr: string) => {
-    const timezone = timezoneStr.toLowerCase() === "local" ?  dayjs.tz.guess() : timezoneStr;
+    const timezone = timezoneStr.toLowerCase() === "local" ? getBrowserTimezone().region : timezoneStr;
     try {
       dayjs().tz(timezone).isValid();
       timeDispatch({ type: "SET_DEFAULT_TIMEZONE", payload: timezone });
diff --git a/app/vmui/packages/vmui/src/state/time/reducer.ts b/app/vmui/packages/vmui/src/state/time/reducer.ts
index a1d8aed80..75d3231b1 100644
--- a/app/vmui/packages/vmui/src/state/time/reducer.ts
+++ b/app/vmui/packages/vmui/src/state/time/reducer.ts
@@ -6,10 +6,10 @@ import {
   getDurationFromPeriod,
   getTimeperiodForDuration,
   getRelativeTime,
-  setTimezone
+  setTimezone,
+  getBrowserTimezone
 } from "../../utils/time";
 import { getQueryStringValue } from "../../utils/query-string";
-import dayjs from "dayjs";
 import { getFromStorage, saveToStorage } from "../../utils/storage";
 
 export interface TimeState {
@@ -29,7 +29,7 @@ export type TimeAction =
   | { type: "SET_TIMEZONE", payload: string }
   | { type: "SET_DEFAULT_TIMEZONE", payload: string }
 
-const timezone = getFromStorage("TIMEZONE") as string || dayjs.tz.guess();
+const timezone = getFromStorage("TIMEZONE") as string || getBrowserTimezone().region;
 setTimezone(timezone);
 
 const defaultDuration = getQueryStringValue("g0.range_input") as string;
diff --git a/app/vmui/packages/vmui/src/utils/time.ts b/app/vmui/packages/vmui/src/utils/time.ts
index 0f2f5b78d..aff82f2aa 100644
--- a/app/vmui/packages/vmui/src/utils/time.ts
+++ b/app/vmui/packages/vmui/src/utils/time.ts
@@ -227,3 +227,22 @@ export const getTimezoneList = (search = "") => {
 export const setTimezone = (timezone: string) => {
   dayjs.tz.setDefault(timezone);
 };
+
+const isValidTimezone = (timezone: string) => {
+  try {
+    dayjs().tz(timezone);
+    return true;
+  } catch (e) {
+    return false;
+  }
+};
+
+export const getBrowserTimezone = () => {
+  const timezone = dayjs.tz.guess();
+  const isValid = isValidTimezone(timezone);
+  return  {
+    isValid,
+    title: isValid ? `Browser Time (${timezone})` : "Browser timezone (UTC)",
+    region: isValid ? timezone : "UTC",
+  };
+};
diff --git a/docs/CHANGELOG.md b/docs/CHANGELOG.md
index d8d219f91..610b0fa1f 100644
--- a/docs/CHANGELOG.md
+++ b/docs/CHANGELOG.md
@@ -35,6 +35,7 @@ The sandbox cluster installation is running under the constant load generated by
 
 * BUGFIX: [MetricsQL](https://docs.victoriametrics.com/MetricsQL.html): properly propagate [label filters](https://docs.victoriametrics.com/keyconcepts/#filtering) from multiple arguments passed to [aggregate functions](https://docs.victoriametrics.com/metricsql/#aggregate-functions). For example, `sum({job="foo"}, {job="bar"}) by (job) + a` was improperly optimized to `sum({job="foo"}, {job="bar"}) by (job) + a{job="foo"}` before being executed. This could lead to unexpected results. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5604).
 * BUGFIX: [vmui](https://docs.victoriametrics.com/#vmui): fix the graph dragging for Firefox and Safari. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5764).
+* BUGFIX: [vmui](https://docs.victoriametrics.com/#vmui): fix handling invalid timezone. See [this issue](https://github.com/VictoriaMetrics/VictoriaMetrics/issues/5732).
 
 ## [v1.97.1](https://github.com/VictoriaMetrics/VictoriaMetrics/releases/tag/v1.97.1)