diff --git a/src/main/scala/org/bitcoins/core/wallet/builder/TxBuilderError.scala b/src/main/scala/org/bitcoins/core/wallet/builder/TxBuilderError.scala
new file mode 100644
index 0000000000..acfea0beb1
--- /dev/null
+++ b/src/main/scala/org/bitcoins/core/wallet/builder/TxBuilderError.scala
@@ -0,0 +1,21 @@
+package org.bitcoins.core.wallet.builder
+
+sealed abstract class TxBuilderError
+
+
+
+
+object TxBuilderError {
+  /** This error indicates that the transaction failed to pass the invariants the user wanted to hold
+    * true after the signing process was complete. An example of this is the transaction is too big,
+    * or the fee level was too high or low.
+    */
+  case object FailedUserInvariants extends TxBuilderError
+
+  /** Means that we gave too many keys for the TxBuilder to use during the signing process for a
+    * utxo. An example of this occurring is if we gave 2 private keys to sign a p2pkh spk.
+    * A p2pkh only requires one private key to sign the utxo.
+    */
+  case object TooManyKeys extends TxBuilderError
+
+}
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