diff --git a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
index 65df6e3c4..22c67c101 100644
--- a/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
+++ b/org.eclipse.jgit.test/tst/org/eclipse/jgit/transport/UploadPackTest.java
@@ -2138,7 +2138,14 @@ public class UploadPackTest {
 				PacketLineIn.END);
 		PacketLineIn pckIn = new PacketLineIn(recvStream);
 
-		assertThat(pckIn.readString(), is("\001packfile"));
+		String s;
+		// When sideband-all is used, object counting happens before
+		// "packfile" is written, and object counting outputs progress
+		// in sideband 2. Skip all these lines.
+		for (s = pckIn.readString(); s.startsWith("\002"); s = pckIn.readString()) {
+			// do nothing
+		}
+		assertThat(s, is("\001packfile"));
 		parsePack(recvStream);
 	}
 
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineOut.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineOut.java
index b07b6f69d..7f837bb84 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineOut.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/PacketLineOut.java
@@ -74,7 +74,7 @@ public class PacketLineOut {
 
 	private boolean flushOnEnd;
 
-	private boolean useSideband;
+	private boolean usingSideband;
 
 	/**
 	 * Create a new packet line writer.
@@ -100,13 +100,25 @@ public class PacketLineOut {
 	}
 
 	/**
-	 * When writing packet lines, use the first byte of each non-flush and
-	 * non-delim packet as a sideband designator.
-	 *
+	 * @return whether to add a sideband designator to each non-flush and
+	 *     non-delim packet
+	 * @see #setUsingSideband
+	 * @since 5.5
+	 */
+	public boolean isUsingSideband() {
+		return usingSideband;
+	}
+
+	/**
+	 * @param value If true, when writing packet lines, add, as the first
+	 *     byte, a sideband designator to each non-flush and non-delim
+	 *     packet. See pack-protocol.txt and protocol-v2.txt from the Git
+	 *     project for more information, specifically the "side-band" and
+	 *     "sideband-all" sections.
 	 * @since 5.5
 	 */
-	public void useSidebandFormat() {
-		this.useSideband = true;
+	public void setUsingSideband(boolean value) {
+		this.usingSideband = value;
 	}
 
 	/**
@@ -151,7 +163,7 @@ public class PacketLineOut {
 	 * @since 4.5
 	 */
 	public void writePacket(byte[] buf, int pos, int len) throws IOException {
-		if (useSideband) {
+		if (usingSideband) {
 			formatLength(len + 5);
 			out.write(lenbuffer, 0, 4);
 			out.write(1);
diff --git a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
index c580ed008..2194f2f30 100644
--- a/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
+++ b/org.eclipse.jgit/src/org/eclipse/jgit/transport/UploadPack.java
@@ -1136,7 +1136,7 @@ public class UploadPack {
 		protocolV2Hook.onFetch(req);
 
 		if (req.getSidebandAll()) {
-			pckOut.useSidebandFormat();
+			pckOut.setUsingSideband(true);
 		}
 
 		// TODO(ifrade): Refactor to pass around the Request object, instead of
@@ -1224,7 +1224,11 @@ public class UploadPack {
 
 			if (sectionSent)
 				pckOut.writeDelim();
-			pckOut.writeString("packfile\n"); //$NON-NLS-1$
+			if (!pckOut.isUsingSideband()) {
+				// sendPack will write "packfile\n" for us if sideband-all is used.
+				// But sideband-all is not used, so we have to write it ourselves.
+				pckOut.writeString("packfile\n"); //$NON-NLS-1$
+			}
 			sendPack(new PackStatistics.Accumulator(),
 					req,
 					req.getClientCapabilities().contains(OPTION_INCLUDE_TAG)
@@ -2293,6 +2297,9 @@ public class UploadPack {
 				}
 			}
 
+			if (pckOut.isUsingSideband()) {
+				pckOut.writeString("packfile\n"); //$NON-NLS-1$
+			}
 			pw.writePack(pm, NullProgressMonitor.INSTANCE, packOut);
 
 			if (msgOut != NullOutputStream.INSTANCE) {