diff --git a/server/controllers/SeriesController.js b/server/controllers/SeriesController.js
index 21c93f332..f4a8aee2c 100644
--- a/server/controllers/SeriesController.js
+++ b/server/controllers/SeriesController.js
@@ -80,7 +80,15 @@ class SeriesController {
     }
     req.series.set(payload)
     if (req.series.changed()) {
-      await req.series.save()
+      try {
+        await req.series.save()
+      } catch (error) {
+        if (error.name === 'SequelizeUniqueConstraintError') {
+          Logger.warn(`[SeriesController] Series name already exists in library: ${payload.name}`)
+          return res.status(400).send('A series with that name already exists in this library')
+        }
+        throw error
+      }
       SocketAuthority.emitter('series_updated', req.series.toOldJSON())
     }
     res.json(req.series.toOldJSON())
diff --git a/test/server/controllers/SeriesController.test.js b/test/server/controllers/SeriesController.test.js
new file mode 100644
index 000000000..d39eb0c8a
--- /dev/null
+++ b/test/server/controllers/SeriesController.test.js
@@ -0,0 +1,185 @@
+const { expect } = require('chai')
+const { Sequelize } = require('sequelize')
+const sinon = require('sinon')
+
+const Database = require('../../../server/Database')
+const SeriesController = require('../../../server/controllers/SeriesController')
+const Logger = require('../../../server/Logger')
+const SocketAuthority = require('../../../server/SocketAuthority')
+
+describe('SeriesController', () => {
+  let library
+
+  beforeEach(async () => {
+    global.ServerSettings = {}
+    Database.sequelize = new Sequelize({ dialect: 'sqlite', storage: ':memory:', logging: false })
+    Database.sequelize.uppercaseFirst = (str) => (str ? `${str[0].toUpperCase()}${str.substr(1)}` : '')
+    await Database.buildModels()
+
+    // Create a library for series to belong to
+    library = await Database.libraryModel.create({ name: 'Test Library', mediaType: 'book' })
+
+    sinon.stub(Logger, 'info')
+    sinon.stub(Logger, 'warn')
+    sinon.stub(Logger, 'error')
+    sinon.stub(SocketAuthority, 'emitter')
+  })
+
+  afterEach(async () => {
+    sinon.restore()
+    await Database.sequelize.sync({ force: true })
+  })
+
+  describe('update', () => {
+    it('should rename a series successfully', async () => {
+      const series = await Database.seriesModel.create({
+        name: 'Old_Name',
+        libraryId: library.id
+      })
+
+      const fakeReq = {
+        series,
+        body: { name: 'New Name' }
+      }
+      const fakeRes = {
+        status: sinon.stub().returnsThis(),
+        send: sinon.spy(),
+        json: sinon.spy()
+      }
+
+      await SeriesController.update(fakeReq, fakeRes)
+
+      expect(fakeRes.json.calledOnce).to.be.true
+      const result = fakeRes.json.firstCall.args[0]
+      expect(result.name).to.equal('New Name')
+      expect(SocketAuthority.emitter.calledWith('series_updated')).to.be.true
+    })
+
+    it('should return 400 when renaming to a name that already exists in the same library', async () => {
+      await Database.seriesModel.create({
+        name: 'Existing Series',
+        libraryId: library.id
+      })
+
+      const seriesToRename = await Database.seriesModel.create({
+        name: 'Old_Series',
+        libraryId: library.id
+      })
+
+      const fakeReq = {
+        series: seriesToRename,
+        body: { name: 'Existing Series' }
+      }
+      const fakeRes = {
+        status: sinon.stub().returnsThis(),
+        send: sinon.spy(),
+        json: sinon.spy()
+      }
+
+      await SeriesController.update(fakeReq, fakeRes)
+
+      expect(fakeRes.status.calledWith(400)).to.be.true
+      expect(fakeRes.send.calledOnce).to.be.true
+      expect(fakeRes.send.firstCall.args[0]).to.include('already exists')
+      expect(fakeRes.json.called).to.be.false
+      expect(SocketAuthority.emitter.called).to.be.false
+    })
+
+    it('should return 400 when no valid fields are provided', async () => {
+      const series = await Database.seriesModel.create({
+        name: 'Test Series',
+        libraryId: library.id
+      })
+
+      const fakeReq = {
+        series,
+        body: { invalidField: 'value' }
+      }
+      const fakeRes = {
+        status: sinon.stub().returnsThis(),
+        send: sinon.spy(),
+        json: sinon.spy()
+      }
+
+      await SeriesController.update(fakeReq, fakeRes)
+
+      expect(fakeRes.status.calledWith(400)).to.be.true
+      expect(fakeRes.send.calledWith('No valid fields to update')).to.be.true
+    })
+
+    it('should not call save when name is unchanged', async () => {
+      const series = await Database.seriesModel.create({
+        name: 'Same Name',
+        libraryId: library.id
+      })
+
+      const fakeReq = {
+        series,
+        body: { name: 'Same Name' }
+      }
+      const fakeRes = {
+        status: sinon.stub().returnsThis(),
+        send: sinon.spy(),
+        json: sinon.spy()
+      }
+
+      await SeriesController.update(fakeReq, fakeRes)
+
+      expect(fakeRes.json.calledOnce).to.be.true
+      expect(SocketAuthority.emitter.called).to.be.false
+    })
+
+    it('should allow same name in different libraries', async () => {
+      const library2 = await Database.libraryModel.create({ name: 'Other Library', mediaType: 'book' })
+
+      await Database.seriesModel.create({
+        name: 'Shared Name',
+        libraryId: library.id
+      })
+
+      const seriesToRename = await Database.seriesModel.create({
+        name: 'Old_Name',
+        libraryId: library2.id
+      })
+
+      const fakeReq = {
+        series: seriesToRename,
+        body: { name: 'Shared Name' }
+      }
+      const fakeRes = {
+        status: sinon.stub().returnsThis(),
+        send: sinon.spy(),
+        json: sinon.spy()
+      }
+
+      await SeriesController.update(fakeReq, fakeRes)
+
+      expect(fakeRes.json.calledOnce).to.be.true
+      const result = fakeRes.json.firstCall.args[0]
+      expect(result.name).to.equal('Shared Name')
+    })
+
+    it('should update description successfully', async () => {
+      const series = await Database.seriesModel.create({
+        name: 'Test Series',
+        libraryId: library.id
+      })
+
+      const fakeReq = {
+        series,
+        body: { description: 'A great series' }
+      }
+      const fakeRes = {
+        status: sinon.stub().returnsThis(),
+        send: sinon.spy(),
+        json: sinon.spy()
+      }
+
+      await SeriesController.update(fakeReq, fakeRes)
+
+      expect(fakeRes.json.calledOnce).to.be.true
+      const result = fakeRes.json.firstCall.args[0]
+      expect(result.description).to.equal('A great series')
+    })
+  })
+})