diff --git a/AK/ByteBuffer.h b/AK/ByteBuffer.h
index 86274d5117..513c505ce1 100644
--- a/AK/ByteBuffer.h
+++ b/AK/ByteBuffer.h
@@ -134,13 +134,12 @@ public:
     [[nodiscard]] void* end_pointer() { return data() + m_size; }
     [[nodiscard]] void const* end_pointer() const { return data() + m_size; }
 
-    // FIXME: Make this function handle failures too.
-    [[nodiscard]] ByteBuffer slice(size_t offset, size_t size) const
+    [[nodiscard]] ErrorOr<ByteBuffer> slice(size_t offset, size_t size) const
     {
         // I cannot hand you a slice I don't have
         VERIFY(offset + size <= this->size());
 
-        return copy(offset_pointer(offset), size).release_value();
+        return copy(offset_pointer(offset), size);
     }
 
     void clear()
diff --git a/Tests/LibC/TestSnprintf.cpp b/Tests/LibC/TestSnprintf.cpp
index 1fba55947d..482d85d2af 100644
--- a/Tests/LibC/TestSnprintf.cpp
+++ b/Tests/LibC/TestSnprintf.cpp
@@ -72,9 +72,9 @@ static bool test_single(Testcase<TArg> const& testcase)
 
     // Checking the results:
     bool return_ok = actual_return == testcase.expected_return;
-    bool canary_1_ok = actual.slice(0, SANDBOX_CANARY_SIZE) == expected.slice(0, SANDBOX_CANARY_SIZE);
-    bool main_ok = actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n) == expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n);
-    bool canary_2_ok = actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE) == expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE);
+    bool canary_1_ok = MUST(actual.slice(0, SANDBOX_CANARY_SIZE)) == MUST(expected.slice(0, SANDBOX_CANARY_SIZE));
+    bool main_ok = MUST(actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)) == MUST(expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n));
+    bool canary_2_ok = MUST(actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)) == MUST(expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE));
     bool buf_ok = actual == expected;
 
     // Evaluate gravity:
@@ -85,20 +85,20 @@ static bool test_single(Testcase<TArg> const& testcase)
     if (!canary_1_ok) {
         warnln("Canary 1 overwritten: Expected {}\n"
                "                   instead got {}",
-            show(expected.slice(0, SANDBOX_CANARY_SIZE)),
-            show(actual.slice(0, SANDBOX_CANARY_SIZE)));
+            show(MUST(expected.slice(0, SANDBOX_CANARY_SIZE))),
+            show(MUST(actual.slice(0, SANDBOX_CANARY_SIZE))));
     }
     if (!main_ok) {
         warnln("Wrong output: Expected {}\n"
                "          instead, got {}",
-            show(expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)),
-            show(actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)));
+            show(MUST(expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n))),
+            show(MUST(actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n))));
     }
     if (!canary_2_ok) {
         warnln("Canary 2 overwritten: Expected {}\n"
                "                  instead, got {}",
-            show(expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)),
-            show(actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)));
+            show(MUST(expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE))),
+            show(MUST(actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE))));
     }
     if (!return_ok) {
         warnln("Wrong return value: Expected {}, got {} instead!", testcase.expected_return, actual_return);
diff --git a/Tests/LibC/TestStrlcpy.cpp b/Tests/LibC/TestStrlcpy.cpp
index 407c307e2f..58106e51a1 100644
--- a/Tests/LibC/TestStrlcpy.cpp
+++ b/Tests/LibC/TestStrlcpy.cpp
@@ -69,9 +69,9 @@ static bool test_single(Testcase const& testcase)
 
     // Checking the results:
     bool return_ok = actual_return == testcase.src_n;
-    bool canary_1_ok = actual.slice(0, SANDBOX_CANARY_SIZE) == expected.slice(0, SANDBOX_CANARY_SIZE);
-    bool main_ok = actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n) == expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n);
-    bool canary_2_ok = actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE) == expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE);
+    bool canary_1_ok = MUST(actual.slice(0, SANDBOX_CANARY_SIZE)) == MUST(expected.slice(0, SANDBOX_CANARY_SIZE));
+    bool main_ok = MUST(actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)) == MUST(expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n));
+    bool canary_2_ok = MUST(actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)) == MUST(expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE));
     bool buf_ok = actual == expected;
 
     // Evaluate gravity:
@@ -82,20 +82,20 @@ static bool test_single(Testcase const& testcase)
     if (!canary_1_ok) {
         warnln("Canary 1 overwritten: Expected canary {}\n"
                "                          instead got {}",
-            show(expected.slice(0, SANDBOX_CANARY_SIZE)),
-            show(actual.slice(0, SANDBOX_CANARY_SIZE)));
+            show(MUST(expected.slice(0, SANDBOX_CANARY_SIZE))),
+            show(MUST(actual.slice(0, SANDBOX_CANARY_SIZE))));
     }
     if (!main_ok) {
         warnln("Wrong output: Expected {}\n"
                "           instead got {}",
-            show(expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)),
-            show(actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n)));
+            show(MUST(expected.slice(SANDBOX_CANARY_SIZE, testcase.dest_n))),
+            show(MUST(actual.slice(SANDBOX_CANARY_SIZE, testcase.dest_n))));
     }
     if (!canary_2_ok) {
         warnln("Canary 2 overwritten: Expected {}\n"
                "                   instead got {}",
-            show(expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)),
-            show(actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE)));
+            show(MUST(expected.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE))),
+            show(MUST(actual.slice(SANDBOX_CANARY_SIZE + testcase.dest_n, SANDBOX_CANARY_SIZE))));
     }
     if (!return_ok) {
         warnln("Wrong return value: Expected {}, got {} instead!", testcase.src_n, actual_return);
diff --git a/Userland/Libraries/LibGemini/Job.cpp b/Userland/Libraries/LibGemini/Job.cpp
index f7cd212d0f..6196abf318 100644
--- a/Userland/Libraries/LibGemini/Job.cpp
+++ b/Userland/Libraries/LibGemini/Job.cpp
@@ -64,7 +64,8 @@ ByteBuffer Job::receive(size_t size)
 {
     ByteBuffer buffer = ByteBuffer::create_uninitialized(size).release_value_but_fixme_should_propagate_errors();
     auto nread = MUST(m_socket->read(buffer)).size();
-    return buffer.slice(0, nread);
+    // FIXME: Propagate errors.
+    return MUST(buffer.slice(0, nread));
 }
 
 bool Job::can_read() const
@@ -101,7 +102,8 @@ void Job::flush_received_buffers()
             continue;
         }
         VERIFY(written < payload.size());
-        payload = payload.slice(written, payload.size() - written);
+        // FIXME: Propagate errors.
+        payload = MUST(payload.slice(written, payload.size() - written));
         return;
     }
 }
diff --git a/Userland/Libraries/LibJS/Runtime/ArrayBuffer.h b/Userland/Libraries/LibJS/Runtime/ArrayBuffer.h
index 6dd93aecb7..8cb6aae419 100644
--- a/Userland/Libraries/LibJS/Runtime/ArrayBuffer.h
+++ b/Userland/Libraries/LibJS/Runtime/ArrayBuffer.h
@@ -130,7 +130,8 @@ Value ArrayBuffer::get_value(size_t byte_index, [[maybe_unused]] bool is_typed_a
 
     // FIXME: Check for shared buffer
 
-    auto raw_value = buffer_impl().slice(byte_index, element_size);
+    // FIXME: Propagate errors.
+    auto raw_value = MUST(buffer_impl().slice(byte_index, element_size));
     return raw_bytes_to_numeric<T>(global_object(), move(raw_value), is_little_endian);
 }
 
@@ -218,7 +219,8 @@ Value ArrayBuffer::get_modify_set_value(size_t byte_index, Value value, ReadWrit
 
     // FIXME: Check for shared buffer
 
-    auto raw_bytes_read = buffer_impl().slice(byte_index, sizeof(T));
+    // FIXME: Propagate errors.
+    auto raw_bytes_read = MUST(buffer_impl().slice(byte_index, sizeof(T)));
     auto raw_bytes_modified = operation(raw_bytes_read, raw_bytes);
     raw_bytes_modified.span().copy_to(buffer_impl().span().slice(byte_index));
 
diff --git a/Userland/Libraries/LibJS/Runtime/AtomicsObject.cpp b/Userland/Libraries/LibJS/Runtime/AtomicsObject.cpp
index 5838ae9bb4..c677a21431 100644
--- a/Userland/Libraries/LibJS/Runtime/AtomicsObject.cpp
+++ b/Userland/Libraries/LibJS/Runtime/AtomicsObject.cpp
@@ -246,7 +246,8 @@ static ThrowCompletionOr<Value> atomic_compare_exchange_impl(GlobalObject& globa
     // 14. Else,
 
     // a. Let rawBytesRead be a List of length elementSize whose elements are the sequence of elementSize bytes starting with block[indexedPosition].
-    auto raw_bytes_read = block.slice(indexed_position, sizeof(T));
+    // FIXME: Propagate errors.
+    auto raw_bytes_read = MUST(block.slice(indexed_position, sizeof(T)));
 
     // b. If ByteListEqual(rawBytesRead, expectedBytes) is true, then
     //    i. Store the individual bytes of replacementBytes into block, starting at block[indexedPosition].
diff --git a/Userland/Libraries/LibSQL/Heap.cpp b/Userland/Libraries/LibSQL/Heap.cpp
index 813909df3e..396172b67f 100644
--- a/Userland/Libraries/LibSQL/Heap.cpp
+++ b/Userland/Libraries/LibSQL/Heap.cpp
@@ -202,7 +202,7 @@ constexpr static int USER_VALUES_OFFSET = 32;
 ErrorOr<void> Heap::read_zero_block()
 {
     auto buffer = TRY(read_block(0));
-    auto file_id_buffer = buffer.slice(0, FILE_ID.length());
+    auto file_id_buffer = TRY(buffer.slice(0, FILE_ID.length()));
     auto file_id = StringView(file_id_buffer);
     if (file_id != FILE_ID) {
         warnln("{}: Zero page corrupt. This is probably not a {} heap file"sv, name(), FILE_ID);
diff --git a/Userland/Libraries/LibTLS/Socket.cpp b/Userland/Libraries/LibTLS/Socket.cpp
index a13e2a4999..fa75c85c54 100644
--- a/Userland/Libraries/LibTLS/Socket.cpp
+++ b/Userland/Libraries/LibTLS/Socket.cpp
@@ -27,8 +27,8 @@ ErrorOr<Bytes> TLSv12::read(Bytes bytes)
         return Bytes {};
     }
 
-    m_context.application_buffer.span().slice(0, size_to_read).copy_to(bytes);
-    m_context.application_buffer = m_context.application_buffer.slice(size_to_read, m_context.application_buffer.size() - size_to_read);
+    TRY(m_context.application_buffer.slice(0, size_to_read)).span().copy_to(bytes);
+    m_context.application_buffer = TRY(m_context.application_buffer.slice(size_to_read, m_context.application_buffer.size() - size_to_read));
     return Bytes { bytes.data(), size_to_read };
 }
 
@@ -47,7 +47,8 @@ String TLSv12::read_line(size_t max_size)
         return {};
 
     String line { bit_cast<char const*>(start), offset, Chomp };
-    m_context.application_buffer = m_context.application_buffer.slice(offset + 1, m_context.application_buffer.size() - offset - 1);
+    // FIXME: Propagate errors.
+    m_context.application_buffer = MUST(m_context.application_buffer.slice(offset + 1, m_context.application_buffer.size() - offset - 1));
 
     return line;
 }
diff --git a/Userland/Libraries/LibTLS/TLSPacketBuilder.h b/Userland/Libraries/LibTLS/TLSPacketBuilder.h
index 6c864a3700..407e30d0f1 100644
--- a/Userland/Libraries/LibTLS/TLSPacketBuilder.h
+++ b/Userland/Libraries/LibTLS/TLSPacketBuilder.h
@@ -85,7 +85,8 @@ public:
     {
         auto length = m_current_length;
         m_current_length = 0;
-        return m_packet_data.slice(0, length);
+        // FIXME: Propagate errors.
+        return MUST(m_packet_data.slice(0, length));
     }
     inline void set(size_t offset, u8 value)
     {
diff --git a/Userland/Libraries/LibTLS/TLSv12.cpp b/Userland/Libraries/LibTLS/TLSv12.cpp
index 9311384002..2f896b4045 100644
--- a/Userland/Libraries/LibTLS/TLSv12.cpp
+++ b/Userland/Libraries/LibTLS/TLSv12.cpp
@@ -92,7 +92,8 @@ void TLSv12::consume(ReadonlyBytes record)
     }
 
     if (index) {
-        m_context.message_buffer = m_context.message_buffer.slice(index, m_context.message_buffer.size() - index);
+        // FIXME: Propagate errors.
+        m_context.message_buffer = MUST(m_context.message_buffer.slice(index, m_context.message_buffer.size() - index));
     }
 }
 
diff --git a/Userland/Utilities/lspci.cpp b/Userland/Utilities/lspci.cpp
index 2b6dd91fe4..53f6b8c958 100644
--- a/Userland/Utilities/lspci.cpp
+++ b/Userland/Utilities/lspci.cpp
@@ -27,7 +27,10 @@ static constexpr StringView format_region = "\tBAR {}: {} region @ {:#x}";
 
 static u32 read_hex_string_from_bytebuffer(ByteBuffer const& buf)
 {
-    return AK::StringUtils::convert_to_uint_from_hex(String(buf.slice(2, buf.size() - 2).bytes())).release_value();
+    // FIXME: Propagate errors.
+    return AK::StringUtils::convert_to_uint_from_hex(
+        String(MUST(buf.slice(2, buf.size() - 2)).bytes()))
+        .release_value();
 }
 
 static u32 convert_sysfs_value_to_uint(String const& value)
diff --git a/Userland/Utilities/pro.cpp b/Userland/Utilities/pro.cpp
index 93201b0f26..775eafa585 100644
--- a/Userland/Utilities/pro.cpp
+++ b/Userland/Utilities/pro.cpp
@@ -132,7 +132,8 @@ private:
 
         if (!m_buffer.is_empty()) {
             auto size = OutputFileStream::write(m_buffer);
-            m_buffer = m_buffer.slice(size, m_buffer.size() - size);
+            // FIXME: Propagate errors.
+            m_buffer = MUST(m_buffer.slice(size, m_buffer.size() - size));
         }
 
         if (!m_buffer.is_empty())