diff --git a/Tests/KeystoneTests/Tests/ViewRelated/NewSupport/SupportAttachmentFilePathTests.swift b/Tests/KeystoneTests/Tests/ViewRelated/NewSupport/SupportAttachmentFilePathTests.swift
new file mode 100644
index 000000000000..f767d14fdf1c
--- /dev/null
+++ b/Tests/KeystoneTests/Tests/ViewRelated/NewSupport/SupportAttachmentFilePathTests.swift
@@ -0,0 +1,78 @@
+import Foundation
+import Testing
+import WordPressAPI
+
+@testable import WordPress
+
+/// Support attachments are handed to `wordpress-rs` as filesystem paths, which it opens directly.
+/// `URL.path()` percent-encodes by default, so a filename needing encoding produced a path that
+/// doesn't exist on disk and failed the whole ticket. Same shape as the media upload bug in #26005.
+struct SupportAttachmentFilePathTests {
+
+    /// A screenshot picked from the library keeps its original filename, and macOS names those
+    /// with spaces.
+    @Test func newTicketDecodesPercentEncodingInAttachmentPaths() {
+        let params = CreateSupportTicketParams(
+            subject: "Subject",
+            message: "Message",
+            application: "jetpack",
+            attachmentURLs: [URL(fileURLWithPath: "/tmp/attachments/Screen Shot 1.png")]
+        )
+
+        #expect(params.attachments == ["/tmp/attachments/Screen Shot 1.png"])
+    }
+
+    /// Characters beyond the space get encoded too — including non-ASCII, which `path()` renders
+    /// as UTF-8 escapes.
+    @Test func newTicketDecodesPercentEncodingBeyondSpaces() {
+        let params = CreateSupportTicketParams(
+            subject: "Subject",
+            message: "Message",
+            application: "jetpack",
+            attachmentURLs: [
+                URL(fileURLWithPath: "/tmp/attachments/100% done.png"),
+                URL(fileURLWithPath: "/tmp/attachments/café.png")
+            ]
+        )
+
+        #expect(params.attachments == ["/tmp/attachments/100% done.png", "/tmp/attachments/café.png"])
+    }
+
+    /// A name needing no encoding has to survive untouched.
+    @Test func newTicketLeavesAnOrdinaryPathAlone() {
+        let params = CreateSupportTicketParams(
+            subject: "Subject",
+            message: "Message",
+            application: "jetpack",
+            attachmentURLs: [URL(fileURLWithPath: "/tmp/attachments/IMG_0001.png")]
+        )
+
+        #expect(params.attachments == ["/tmp/attachments/IMG_0001.png"])
+    }
+
+    /// The reply path builds a different params type, so it needs its own coverage.
+    @Test func replyDecodesPercentEncodingInAttachmentPaths() {
+        let params = AddMessageToSupportConversationParams(
+            message: "Message",
+            attachmentURLs: [URL(fileURLWithPath: "/tmp/attachments/Screen Shot 1.png")]
+        )
+
+        #expect(params.attachments == ["/tmp/attachments/Screen Shot 1.png"])
+    }
+
+    @Test func replyLeavesAnOrdinaryPathAlone() {
+        let params = AddMessageToSupportConversationParams(
+            message: "Message",
+            attachmentURLs: [URL(fileURLWithPath: "/tmp/attachments/IMG_0001.png")]
+        )
+
+        #expect(params.attachments == ["/tmp/attachments/IMG_0001.png"])
+    }
+
+    /// No attachments is the common case and must not trip the mapping.
+    @Test func emptyAttachmentsProduceNoPaths() {
+        let params = AddMessageToSupportConversationParams(message: "Message", attachmentURLs: [])
+
+        #expect(params.attachments.isEmpty)
+    }
+}
diff --git a/WordPress/Classes/ViewRelated/NewSupport/SupportDataProvider.swift b/WordPress/Classes/ViewRelated/NewSupport/SupportDataProvider.swift
index ea4c6df0161f..83c84c7cdcc0 100644
--- a/WordPress/Classes/ViewRelated/NewSupport/SupportDataProvider.swift
+++ b/WordPress/Classes/ViewRelated/NewSupport/SupportDataProvider.swift
@@ -305,7 +305,7 @@ actor WpSupportConversationDataProvider: SupportConversationDataProvider {
             subject: subject,
             message: message,
             application: "jetpack",
-            attachments: attachments.map { $0.path() }
+            attachmentURLs: attachments
         )
 
         return try await self.wpcomClient.api
@@ -323,7 +323,7 @@ actor WpSupportConversationDataProvider: SupportConversationDataProvider {
     ) async throws -> Conversation {
         let params = AddMessageToSupportConversationParams(
             message: message,
-            attachments: attachments.map { $0.path() }
+            attachmentURLs: attachments
         )
 
         let conversation = try await self.wpcomClient.api
@@ -336,6 +336,33 @@ actor WpSupportConversationDataProvider: SupportConversationDataProvider {
     }
 }
 
+// Not `private`: the file-path handling below is covered by `SupportAttachmentFilePathTests`.
+//
+// Both params types carry `attachments` as filesystem paths, which `wordpress-rs` turns into
+// `MultipartFormFile.file_path` and opens directly. `URL.path()` percent-encodes by default, so a
+// filename with a space — a macOS screenshot, say — becomes a path that doesn't exist on disk and
+// the whole request fails with `MediaFileNotFound`. These initializers own that conversion so the
+// call sites can pass URLs.
+extension CreateSupportTicketParams {
+    init(subject: String, message: String, application: String, attachmentURLs: [URL]) {
+        self.init(
+            subject: subject,
+            message: message,
+            application: application,
+            attachments: attachmentURLs.map { $0.path(percentEncoded: false) }
+        )
+    }
+}
+
+extension AddMessageToSupportConversationParams {
+    init(message: String, attachmentURLs: [URL]) {
+        self.init(
+            message: message,
+            attachments: attachmentURLs.map { $0.path(percentEncoded: false) }
+        )
+    }
+}
+
 actor WpDiagnosticsDataProvider: DiagnosticsDataProvider {
     func fetchDiskCacheUsage() async throws -> WordPressCoreProtocols.DiskCacheUsage {
         try await DiskCache.shared.diskUsage()