From 77ea64792467ff60e8e4007ad48a57aa1d42fecb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eren=20=C3=87akar?= <hey@erencakar.com>
Date: Fri, 5 Jun 2026 02:24:33 +0300
Subject: [PATCH 1/2] Ensure UTC session timezone in PrismaPg connections
 (#4285)

@prisma/adapter-pg's internal formatDateTime function converts JS Date
objects to PostgreSQL TIMESTAMPTZ strings without appending a timezone
offset. When the database session timezone is not UTC (e.g. UTC+8),
PostgreSQL misinterprets the value, causing stored timestamps to be
shifted backward.

Fix by appending 'options=-c timezone=UTC' to the connection URL in all
three places that create a PrismaPg adapter, ensuring every session
interprets timezone-naive timestamp strings as UTC.
---
 scripts/check-db.js   |  8 ++++++++
 scripts/seed/index.ts | 10 +++++++++-
 src/lib/prisma.ts     | 29 +++++++++++++++++++++++++++--
 3 files changed, 44 insertions(+), 3 deletions(-)

diff --git a/scripts/check-db.js b/scripts/check-db.js
index 100cba0317..b0fa287226 100644
--- a/scripts/check-db.js
+++ b/scripts/check-db.js
@@ -15,6 +15,14 @@ if (process.env.SKIP_DB_CHECK) {
 
 const url = new URL(process.env.DATABASE_URL);
 
+const existingOptions = url.searchParams.get('options') || '';
+if (!existingOptions.includes('timezone')) {
+  url.searchParams.set(
+    'options',
+    existingOptions ? `${existingOptions} -c timezone=UTC` : '-c timezone=UTC',
+  );
+}
+
 const adapter = new PrismaPg(
   { connectionString: url.toString() },
   { schema: url.searchParams.get('schema') },
diff --git a/scripts/seed/index.ts b/scripts/seed/index.ts
index 2357ca4d9d..5a8f899caa 100644
--- a/scripts/seed/index.ts
+++ b/scripts/seed/index.ts
@@ -291,7 +291,15 @@ function createPrismaClient(): PrismaClient {
     );
   }
 
-  const adapter = new PrismaPg({ connectionString: url }, { schema });
+  const existingOptions = connectionUrl.searchParams.get('options') || '';
+  if (!existingOptions.includes('timezone')) {
+    connectionUrl.searchParams.set(
+      'options',
+      existingOptions ? `${existingOptions} -c timezone=UTC` : '-c timezone=UTC',
+    );
+  }
+
+  const adapter = new PrismaPg({ connectionString: connectionUrl.toString() }, { schema });
 
   return new PrismaClient({
     adapter,
diff --git a/src/lib/prisma.ts b/src/lib/prisma.ts
index 6cdb33cfd2..09db9b8dae 100644
--- a/src/lib/prisma.ts
+++ b/src/lib/prisma.ts
@@ -551,7 +551,21 @@ function getClient() {
 
   const schema = getSchema();
 
-  const baseAdapter = new PrismaPg({ connectionString: url }, { schema });
+  // Ensure consistent UTC session timezone so that TIMESTAMPTZ values
+  // written by @prisma/adapter-pg are not mis-interpreted by PostgreSQL.
+  // The adapter's formatDateTime omits the timezone offset, causing
+  // PostgreSQL to assume the session timezone (default: server timezone).
+  // See https://github.com/umami-software/umami/issues/4285
+  const connectionUrl = new URL(url);
+  const existingOptions = connectionUrl.searchParams.get('options') || '';
+  if (!existingOptions.includes('timezone')) {
+    connectionUrl.searchParams.set(
+      'options',
+      existingOptions ? `${existingOptions} -c timezone=UTC` : '-c timezone=UTC',
+    );
+  }
+
+  const baseAdapter = new PrismaPg({ connectionString: connectionUrl.toString() }, { schema });
 
   const baseClient = new PrismaClient({
     adapter: baseAdapter,
@@ -569,7 +583,18 @@ function getClient() {
     return baseClient;
   }
 
-  const replicaAdapter = new PrismaPg({ connectionString: replicaUrl }, { schema });
+  const replicaConnectionUrl = new URL(replicaUrl);
+  const replicaExistingOptions = replicaConnectionUrl.searchParams.get('options') || '';
+  if (!replicaExistingOptions.includes('timezone')) {
+    replicaConnectionUrl.searchParams.set(
+      'options',
+      replicaExistingOptions
+        ? `${replicaExistingOptions} -c timezone=UTC`
+        : '-c timezone=UTC',
+    );
+  }
+
+  const replicaAdapter = new PrismaPg({ connectionString: replicaConnectionUrl.toString() }, { schema });
 
   const replicaClient = new PrismaClient({
     adapter: replicaAdapter,

From 99818c970db22cc52abcafa0f2ef71b08f445042 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Eren=20=C3=87akar?= <super.erencakar@gmail.com>
Date: Fri, 5 Jun 2026 02:31:39 +0300
Subject: [PATCH 2/2] Update src/lib/prisma.ts

Co-authored-by: greptile-apps[bot] <165735046+greptile-apps[bot]@users.noreply.github.com>
---
 src/lib/prisma.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/lib/prisma.ts b/src/lib/prisma.ts
index 09db9b8dae..57e4074659 100644
--- a/src/lib/prisma.ts
+++ b/src/lib/prisma.ts
@@ -558,7 +558,7 @@ function getClient() {
   // See https://github.com/umami-software/umami/issues/4285
   const connectionUrl = new URL(url);
   const existingOptions = connectionUrl.searchParams.get('options') || '';
-  if (!existingOptions.includes('timezone')) {
+  if (!/(^|\s)-c\s+timezone=/i.test(existingOptions)) {
     connectionUrl.searchParams.set(
       'options',
       existingOptions ? `${existingOptions} -c timezone=UTC` : '-c timezone=UTC',