diff --git a/payjoin-ffi/javascript/test/integration.test.ts b/payjoin-ffi/javascript/test/integration.test.ts
index fb607b83f..277d4c477 100644
--- a/payjoin-ffi/javascript/test/integration.test.ts
+++ b/payjoin-ffi/javascript/test/integration.test.ts
@@ -504,18 +504,25 @@ function testFfiValidation(payjoin: PayjoinModule): void {
         assert.strictEqual(inner.tag, "WeightOutOfRange");
     }
 
-    const pjUri = payjoin.Uri.parse(
+    const v1PjUri = payjoin.Uri.parse(
         "bitcoin:12c6DSiU4Rq3P4ZxziKxzrL5LmMBrzjrJX?amount=1&pj=https://example.com",
     ).checkPjSupported();
+    const v2PjUri = payjoin.Uri.parse(
+        "bitcoin:2N47mmrWXsNBvQR6k78hWJoTji57zXwNcU7?pjos=0&pj=HTTPS://PAYJO.IN/TXJCGKTKXLUUZ%23EX1WKV8CEC-OH1QYPM59NK2LXXS4890SUAXXYT25Z2VAPHP0X7YEYCJXGWAG6UG9ZU6NQ-RK1Q0DJS3VVDXWQQTLQ8022QGXSX7ML9PHZ6EDSF6AKEWQG758JPS2EV",
+    ).checkPjSupported();
     const psbt = testUtils.originalPsbt();
     assert.throws(() => {
-        new payjoin.SenderBuilder(psbt, pjUri).buildRecommended(
+        new payjoin.SenderBuilder(psbt, v2PjUri).buildRecommended(
             18446744073709551615n,
         );
     }, /RuntimeError/);
 
     assert.throws(() => {
-        pjUri.setAmountSats(tooLargeAmount);
+        new payjoin.SenderBuilder(psbt, v1PjUri);
+    }, /SenderInputError\.Build/);
+
+    assert.throws(() => {
+        v1PjUri.setAmountSats(tooLargeAmount);
     }, /AmountOutOfRange/);
 }
 
diff --git a/payjoin-ffi/src/send/mod.rs b/payjoin-ffi/src/send/mod.rs
index bccbead8b..a3a949629 100644
--- a/payjoin-ffi/src/send/mod.rs
+++ b/payjoin-ffi/src/send/mod.rs
@@ -356,7 +356,8 @@ impl SenderBuilder {
         let psbt = payjoin::bitcoin::psbt::Psbt::from_str(psbt.as_str())
             .map_err(PsbtParseError::from)
             .map_err(SenderInputError::Psbt)?;
-        let builder = payjoin::send::v2::SenderBuilder::new(psbt, Arc::unwrap_or_clone(uri).into());
+        let builder = payjoin::send::v2::SenderBuilder::new(psbt, Arc::unwrap_or_clone(uri).into())
+            .map_err(|e| SenderInputError::Build(Arc::new(e.into())))?;
         Ok(builder.into())
     }
 
diff --git a/payjoin/src/core/send/error.rs b/payjoin/src/core/send/error.rs
index 7143cc9cb..319160f71 100644
--- a/payjoin/src/core/send/error.rs
+++ b/payjoin/src/core/send/error.rs
@@ -18,6 +18,8 @@ pub(crate) enum InternalBuildSenderError {
     InvalidOriginalInput(crate::psbt::PsbtInputsError),
     InconsistentOriginalPsbt(crate::psbt::InconsistentPsbt),
     OriginalTxinNonAllSighashType,
+    #[cfg(all(feature = "v1", feature = "v2"))]
+    UnsupportedVersion,
     NoInputs,
     PayeeValueNotEqual,
     NoOutputs,
@@ -49,6 +51,8 @@ impl fmt::Display for BuildSenderError {
             InvalidOriginalInput(e) => write!(f, "an input in the original transaction is invalid: {e:#?}"),
             InconsistentOriginalPsbt(e) => write!(f, "the original transaction is inconsistent: {e:#?}"),
             OriginalTxinNonAllSighashType => write!(f, "an input in the original transaction requests a sighash type other than SIGHASH_ALL"),
+            #[cfg(all(feature = "v1", feature = "v2"))]
+            UnsupportedVersion => write!(f, "v2 sender does not support v1 payjoin URIs"),
             NoInputs => write!(f, "the original transaction has no inputs"),
             PayeeValueNotEqual => write!(f, "the value in original transaction doesn't equal value requested in the payment link"),
             NoOutputs => write!(f, "the original transaction has no outputs"),
@@ -72,6 +76,8 @@ impl std::error::Error for BuildSenderError {
             InvalidOriginalInput(error) => Some(error),
             InconsistentOriginalPsbt(error) => Some(error),
             OriginalTxinNonAllSighashType => None,
+            #[cfg(all(feature = "v1", feature = "v2"))]
+            UnsupportedVersion => None,
             NoInputs => None,
             PayeeValueNotEqual => None,
             NoOutputs => None,
diff --git a/payjoin/src/core/send/v2/mod.rs b/payjoin/src/core/send/v2/mod.rs
index 982565a25..f33691c3f 100644
--- a/payjoin/src/core/send/v2/mod.rs
+++ b/payjoin/src/core/send/v2/mod.rs
@@ -71,12 +71,12 @@ impl SenderBuilder {
     ///
     /// Call [`SenderBuilder::build_recommended()`] or other `build` methods
     /// to create a [`Sender`]
-    pub fn new(psbt: Psbt, uri: PjUri) -> Self {
+    pub fn new(psbt: Psbt, uri: PjUri) -> Result<Self, BuildSenderError> {
         match uri.extras().pj_param() {
             #[cfg(feature = "v1")]
-            crate::uri::PjParam::V1(_) => unimplemented!("V2 SenderBuilder only supports v2 URLs"),
+            crate::uri::PjParam::V1(_) => Err(InternalBuildSenderError::UnsupportedVersion.into()),
             crate::uri::PjParam::V2(pj_param) =>
-                Self::from_parts(psbt, pj_param, uri.address(), uri.amount()),
+                Ok(Self::from_parts(psbt, pj_param, uri.address(), uri.amount())),
         }
     }
 
@@ -721,6 +721,24 @@ mod test {
         Ok(())
     }
 
+    #[cfg(feature = "v1")]
+    #[test]
+    fn v1_uri_returns_error_instead_of_panicking() {
+        const V1_PJ_URI: &str =
+            "bitcoin:2N47mmrWXsNBvQR6k78hWJoTji57zXwNcU7?amount=0.02&pjos=0&pj=HTTPS://EXAMPLE.COM/";
+        let uri = crate::Uri::try_from(V1_PJ_URI)
+            .expect("valid URI")
+            .assume_checked()
+            .check_pj_supported()
+            .expect("payjoin should be supported");
+
+        let err = SenderBuilder::new(PARSED_ORIGINAL_PSBT.clone(), uri)
+            .err()
+            .expect("v1 URI should be rejected");
+
+        assert_eq!(err.to_string(), "v2 sender does not support v1 payjoin URIs");
+    }
+
     #[test]
     fn test_v2_sender_builder() {
         let address = Address::from_str("2N47mmrWXsNBvQR6k78hWJoTji57zXwNcU7")
@@ -736,6 +754,7 @@ mod test {
             .expect("receiver should succeed")
             .pj_uri();
         let req_ctx = SenderBuilder::new(PARSED_ORIGINAL_PSBT.clone(), pj_uri.clone())
+            .expect("v2 URI should be supported")
             .build_recommended(FeeRate::BROADCAST_MIN)
             .expect("build on test vector should succeed")
             .save(&InMemoryPersister::default())
@@ -757,6 +776,7 @@ mod test {
         assert_eq!(req_ctx.session_context.psbt_ctx.min_fee_rate, FeeRate::from_sat_per_kwu(250));
         // ensure that the other builder methods also enable output substitution
         let req_ctx = SenderBuilder::new(PARSED_ORIGINAL_PSBT.clone(), pj_uri.clone())
+            .expect("v2 URI should be supported")
             .build_non_incentivizing(FeeRate::BROADCAST_MIN)
             .expect("build on test vector should succeed")
             .save(&InMemoryPersister::default())
@@ -766,6 +786,7 @@ mod test {
             OutputSubstitution::Enabled
         );
         let req_ctx = SenderBuilder::new(PARSED_ORIGINAL_PSBT.clone(), pj_uri.clone())
+            .expect("v2 URI should be supported")
             .build_with_additional_fee(Amount::ZERO, Some(0), FeeRate::BROADCAST_MIN, false)
             .expect("build on test vector should succeed")
             .save(&InMemoryPersister::default())
@@ -776,6 +797,7 @@ mod test {
         );
         // ensure that a v2 sender may still disable output substitution if they prefer.
         let req_ctx = SenderBuilder::new(PARSED_ORIGINAL_PSBT.clone(), pj_uri)
+            .expect("v2 URI should be supported")
             .always_disable_output_substitution()
             .build_recommended(FeeRate::BROADCAST_MIN)
             .expect("build on test vector should succeed")
diff --git a/payjoin/src/core/send/v2/session.rs b/payjoin/src/core/send/v2/session.rs
index 78126bced..289189f98 100644
--- a/payjoin/src/core/send/v2/session.rs
+++ b/payjoin/src/core/send/v2/session.rs
@@ -320,6 +320,7 @@ mod tests {
                 .check_pj_supported()
                 .expect("Payjoin to be supported"),
         )
+        .expect("v2 URI should be supported")
         .build_recommended(FeeRate::BROADCAST_MIN)
         .unwrap()
         .save(&InMemoryPersister::default())
@@ -354,6 +355,7 @@ mod tests {
                 .check_pj_supported()
                 .expect("Payjoin to be supported"),
         )
+        .expect("v2 URI should be supported")
         .build_recommended(FeeRate::BROADCAST_MIN)
         .unwrap()
         .save(&InMemoryPersister::default())
@@ -390,6 +392,7 @@ mod tests {
                 .check_pj_supported()
                 .expect("Payjoin to be supported"),
         )
+        .expect("v2 URI should be supported")
         .build_recommended(FeeRate::BROADCAST_MIN)
         .unwrap()
         .save(&InMemoryPersister::default())
@@ -437,6 +440,7 @@ mod tests {
                 .check_pj_supported()
                 .expect("Payjoin to be supported"),
         )
+        .expect("v2 URI should be supported")
         .build_recommended(FeeRate::BROADCAST_MIN)
         .unwrap()
         .save(&InMemoryPersister::default())
@@ -479,6 +483,7 @@ mod tests {
                 .check_pj_supported()
                 .expect("Payjoin to be supported"),
         )
+        .expect("v2 URI should be supported")
         .build_recommended(FeeRate::BROADCAST_MIN)
         .unwrap()
         .save(&InMemoryPersister::default())
diff --git a/payjoin/tests/integration.rs b/payjoin/tests/integration.rs
index 39f361cbd..e79beaf5d 100644
--- a/payjoin/tests/integration.rs
+++ b/payjoin/tests/integration.rs
@@ -317,7 +317,7 @@ mod integration {
                 // Inside the Sender:
                 let psbt = build_original_psbt(&sender, &expired_receiver.pj_uri())?;
                 // Test that an expired pj_url errors
-                let expired_req_ctx = SenderBuilder::new(psbt, expired_receiver.pj_uri())
+                let expired_req_ctx = SenderBuilder::new(psbt, expired_receiver.pj_uri())?
                     .build_non_incentivizing(FeeRate::BROADCAST_MIN)?
                     .save(&send_persister)?;
 
@@ -390,7 +390,7 @@ mod integration {
                     .check_pj_supported()
                     .map_err(|e| e.to_string())?;
                 let psbt = build_sweep_psbt(&sender, &pj_uri)?;
-                let req_ctx = SenderBuilder::new(psbt, pj_uri)
+                let req_ctx = SenderBuilder::new(psbt, pj_uri)?
                     .build_recommended(FeeRate::BROADCAST_MIN)?
                     .save(&sender_persister)?;
                 let (Request { url, body, content_type, .. }, send_ctx) =
@@ -841,7 +841,7 @@ mod integration {
                 .check_pj_supported()
                 .map_err(|e| e.to_string())?;
             let psbt = build_sweep_psbt(sender, &pj_uri)?;
-            let req_ctx = SenderBuilder::new(psbt, pj_uri)
+            let req_ctx = SenderBuilder::new(psbt, pj_uri)?
                 .build_recommended(FeeRate::BROADCAST_MIN)?
                 .save(send_persister)?;
             let (Request { url, body, content_type, .. }, send_ctx) =