diff --git a/RELEASE-NOTES.txt b/RELEASE-NOTES.txt
index 95c054af61d8..32d5ac9c9409 100644
--- a/RELEASE-NOTES.txt
+++ b/RELEASE-NOTES.txt
@@ -5,6 +5,7 @@
 * [**] Reader post details Comments snippet: added ability to manage conversation subscription and notifications. [#17749]
 * [**] Accessibility: VoiceOver improvements on Activity Log and Schedule Post calendars [#17756, #17761]
 * [*] Weekly Roundup: Fix a crash which was preventing weekly roundup notifications from appearing [#17765]
+* [*] Share Sheet from Photos: Fix an issue where certain filenames would not upload or render in Post [#16773]
 
 19.0
 -----
diff --git a/WordPress/Classes/Extensions/String+Files.swift b/WordPress/Classes/Extensions/String+Files.swift
index 494e0101f3ef..88b0d3a781ae 100644
--- a/WordPress/Classes/Extensions/String+Files.swift
+++ b/WordPress/Classes/Extensions/String+Files.swift
@@ -13,4 +13,17 @@ extension String {
             fileExtension as CFString,
             nil)?.takeUnretainedValue() as String?
     }
+
+    /// Lightweight swift version of wordpress formatting.php sanitize_file_name function
+    ///
+    /// - Returns: sanitized filename to match api
+    func sanitizeFileName() -> String {
+        var fileName = folding(options: .diacriticInsensitive, locale: .current)
+
+        let specialChars: Set<Character> = ["?", "[", "]", "/", "\\", "=", "<", ">", ":", ";", ",", "'", "\"", "&", "$", "#", "*", "(", ")", "|", "~", "`", "!", "{", "}", "%", "+", "’", "«", "»", "”", "“"]
+        fileName.removeAll(where: { specialChars.contains($0) })
+
+        return fileName
+    }
+
 }
diff --git a/WordPress/WordPress.xcodeproj/project.pbxproj b/WordPress/WordPress.xcodeproj/project.pbxproj
index b29bbe76a04d..3ffdd1df341f 100644
--- a/WordPress/WordPress.xcodeproj/project.pbxproj
+++ b/WordPress/WordPress.xcodeproj/project.pbxproj
@@ -2268,6 +2268,8 @@
 		DC3B9B2C27739760003F7249 /* TimeZoneSelectorViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC3B9B2B27739760003F7249 /* TimeZoneSelectorViewModel.swift */; };
 		DC3B9B2D27739760003F7249 /* TimeZoneSelectorViewModel.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC3B9B2B27739760003F7249 /* TimeZoneSelectorViewModel.swift */; };
 		DC3B9B2F27739887003F7249 /* TimeZoneSelectorViewModelTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC3B9B2E27739887003F7249 /* TimeZoneSelectorViewModelTests.swift */; };
+		DC5FE07F2795C6A4006D5779 /* String+Files.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7360018E20A265C7001E5E31 /* String+Files.swift */; };
+		DC5FE0802795C6A5006D5779 /* String+Files.swift in Sources */ = {isa = PBXBuildFile; fileRef = 7360018E20A265C7001E5E31 /* String+Files.swift */; };
 		DC76668326FD9AC9009254DD /* TimeZoneRow.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC76668126FD9AC8009254DD /* TimeZoneRow.swift */; };
 		DC76668426FD9AC9009254DD /* TimeZoneRow.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC76668126FD9AC8009254DD /* TimeZoneRow.swift */; };
 		DC76668526FD9AC9009254DD /* TimeZoneTableViewCell.swift in Sources */ = {isa = PBXBuildFile; fileRef = DC76668226FD9AC9009254DD /* TimeZoneTableViewCell.swift */; };
@@ -8508,7 +8510,7 @@
 			path = Classes;
 			sourceTree = "<group>";
 		};
-		29B97314FDCFA39411CA2CEA = {
+		29B97314FDCFA39411CA2CEA /* CustomTemplate */ = {
 			isa = PBXGroup;
 			children = (
 				3F20FDF3276BF21000DA3CAD /* Packages */,
@@ -15299,7 +15301,7 @@
 				bg,
 				sk,
 			);
-			mainGroup = 29B97314FDCFA39411CA2CEA;
+			mainGroup = 29B97314FDCFA39411CA2CEA /* CustomTemplate */;
 			packageReferences = (
 				3FF1442E266F3C2400138163 /* XCRemoteSwiftPackageReference "ScreenObject" */,
 				3FC2C33B26C4CF0A00C6D98F /* XCRemoteSwiftPackageReference "XCUITestHelpers" */,
@@ -18723,6 +18725,7 @@
 				74021A14202E1393006CC39F /* ShareExtensionEditorViewController.swift in Sources */,
 				CBF6201426E8FB8A0061A1F8 /* RemotePost+ShareData.swift in Sources */,
 				CE39E17320CB117B00CABA05 /* RemoteBlog+Capabilities.swift in Sources */,
+				DC5FE0802795C6A5006D5779 /* String+Files.swift in Sources */,
 				74021A0F202E1370006CC39F /* ExtensionTransitioningManager.swift in Sources */,
 				74E44AD92031ED2300556205 /* WordPressDraft-Lumberjack.m in Sources */,
 				741AF3A5202F3E2A00C771A5 /* Tracks+DraftAction.swift in Sources */,
@@ -18809,6 +18812,7 @@
 				170BEC872391530D0017AEC1 /* FeatureFlagOverrideStore.swift in Sources */,
 				CBF6201326E8FB520061A1F8 /* RemotePost+ShareData.swift in Sources */,
 				74448F542044BC7600BD4CDA /* CategoryTree.swift in Sources */,
+				DC5FE07F2795C6A4006D5779 /* String+Files.swift in Sources */,
 				74402F2A200528F200A1D4A2 /* ExtensionPresentationController.swift in Sources */,
 				B5BEA55F1C7CE6D100C8035B /* Constants.m in Sources */,
 				CE39E17220CB117B00CABA05 /* RemoteBlog+Capabilities.swift in Sources */,
diff --git a/WordPress/WordPressShareExtension/AppExtensionsService.swift b/WordPress/WordPressShareExtension/AppExtensionsService.swift
index 2f698df2db14..80ee7d01dadf 100644
--- a/WordPress/WordPressShareExtension/AppExtensionsService.swift
+++ b/WordPress/WordPressShareExtension/AppExtensionsService.swift
@@ -335,7 +335,12 @@ extension AppExtensionsService {
                                 mediaUploadOp.height = height
                             }
 
-                            ShareMediaFileManager.shared.removeFromUploadDirectory(fileName: localFileName)
+                            // localURL lastPathComponent is the original unsanitized filename
+                            if let localURL = mediaUploadOp.localURL, let url = URL(string: localURL) {
+                                ShareMediaFileManager.shared.removeFromUploadDirectory(fileName: url.lastPathComponent)
+                            } else {
+                                ShareMediaFileManager.shared.removeFromUploadDirectory(fileName: localFileName)
+                            }
                         }
                     }
                 })
@@ -366,7 +371,12 @@ fileprivate extension AppExtensionsService {
         var allRemoteMedia = [RemoteMedia]()
         localMediaFileURLs.forEach { tempFilePath in
             let remoteMedia = RemoteMedia()
+
+            // Use a percent encoded + sanitized filename as the remoteMedia file.
             remoteMedia.file = tempFilePath.lastPathComponent
+                                            .addingPercentEncoding(withAllowedCharacters: .urlPathAllowed)?
+                                            .sanitizeFileName()
+
             remoteMedia.mimeType = Constants.mimeType
             remoteMedia.localURL = tempFilePath
             allRemoteMedia.append(remoteMedia)
diff --git a/WordPress/WordPressShareExtension/ShareExtensionEditorViewController.swift b/WordPress/WordPressShareExtension/ShareExtensionEditorViewController.swift
index 8fbc3ec73e90..bbc4ab6d0406 100644
--- a/WordPress/WordPressShareExtension/ShareExtensionEditorViewController.swift
+++ b/WordPress/WordPressShareExtension/ShareExtensionEditorViewController.swift
@@ -989,7 +989,12 @@ extension ShareExtensionEditorViewController {
         let attachment = richTextView.replaceWithImage(at: self.richTextView.selectedRange, sourceURL: url, placeHolderImage: Assets.defaultMissingImage)
 
         attachment.size = .full
-        attachment.uploadID = url.lastPathComponent // Use the filename as the uploadID here.
+
+        // Use a percent encoded + sanitized filename as the uploadID here.
+        attachment.uploadID = url.lastPathComponent
+                                    .addingPercentEncoding(withAllowedCharacters: .urlPathAllowed)?
+                                    .sanitizeFileName()
+
         richTextView.refresh(attachment)
     }
 }
diff --git a/WordPress/WordPressTest/Extensions/StringExtensionsTests.swift b/WordPress/WordPressTest/Extensions/StringExtensionsTests.swift
index c921c871875f..ebf1f6de1923 100644
--- a/WordPress/WordPressTest/Extensions/StringExtensionsTests.swift
+++ b/WordPress/WordPressTest/Extensions/StringExtensionsTests.swift
@@ -40,4 +40,30 @@ class StringExtensionsTests: XCTestCase {
     func testLinkifyingPlainText() {
         XCTAssertEqual(text.stringWithAnchoredLinks(), text, "Oh noes!")
     }
+
+    func testSanitizeFileName() {
+        // https://github.com/wordpress-mobile/WordPress-iOS/issues/16773
+        // Given Percent encoded string
+        let fileNameRaw = "crown-house_%C2%A9-francesco-russo_websize_002-1-1"
+
+        // When sanitizing
+        // Then sanitizeFileName returns strings without %
+        XCTAssertEqual(fileNameRaw.sanitizeFileName(), "crown-house_C2A9-francesco-russo_websize_002-1-1")
+
+
+        // Given a filename with accents
+        let fileNameWithAccents = "Français"
+
+        // When sanitizing
+        // Then sanitizeFileName returns fileName without accents
+        XCTAssertEqual(fileNameWithAccents.sanitizeFileName(), "Francais")
+
+
+        // Given a filename with only special characters
+        let fileNameWithOnlySpecialChars = "?[]/\\=<>:;,'\"&$#*()|~`!{}%+’«»”“"
+
+        // When sanitizing
+        // Then sanitizeFileName returns empty string
+        XCTAssertEqual(fileNameWithOnlySpecialChars.sanitizeFileName(), "")
+    }
 }