diff --git a/src/main/java/org/qortal/block/Block.java b/src/main/java/org/qortal/block/Block.java
index 4614c81c..4ad7894f 100644
--- a/src/main/java/org/qortal/block/Block.java
+++ b/src/main/java/org/qortal/block/Block.java
@@ -304,8 +304,10 @@ public class Block {
 
 		// Fetch our list of online accounts
 		List<OnlineAccountData> onlineAccounts = Controller.getInstance().getOnlineAccounts();
-		if (onlineAccounts.isEmpty())
-			throw new IllegalStateException("No online accounts - not even our own?");
+		if (onlineAccounts.isEmpty()) {
+			LOGGER.error("No online accounts - not even our own?");
+			return null;
+		}
 
 		// Find newest online accounts timestamp
 		long onlineAccountsTimestamp = 0;
@@ -350,8 +352,10 @@ public class Block {
 
 		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
 		int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, minter.getPublicKey());
-		if (minterLevel == 0)
-			throw new IllegalStateException("Minter effective level returned zero?");
+		if (minterLevel == 0) {
+			LOGGER.error("Minter effective level returned zero?");
+			return null;
+		}
 
 		long timestamp = calcTimestamp(parentBlockData, minter.getPublicKey(), minterLevel);
 
@@ -419,8 +423,10 @@ public class Block {
 
 		// Qortal: minter is always a reward-share, so find actual minter and get their effective minting level
 		int minterLevel = Account.getRewardShareEffectiveMintingLevel(repository, minter.getPublicKey());
-		if (minterLevel == 0)
-			throw new IllegalStateException("Minter effective level returned zero?");
+		if (minterLevel == 0){
+			LOGGER.error("Minter effective level returned zero?");
+			return null;
+		}
 
 		long timestamp = calcTimestamp(parentBlockData, minter.getPublicKey(), minterLevel);
 
diff --git a/src/main/java/org/qortal/block/BlockMinter.java b/src/main/java/org/qortal/block/BlockMinter.java
index 48bcb967..c5e64728 100644
--- a/src/main/java/org/qortal/block/BlockMinter.java
+++ b/src/main/java/org/qortal/block/BlockMinter.java
@@ -163,10 +163,18 @@ public class BlockMinter extends Thread {
 					// First block does the AT heavy-lifting
 					if (newBlocks.isEmpty()) {
 						Block newBlock = Block.mint(repository, previousBlock.getBlockData(), mintingAccount);
+						if (newBlock == null)
+							// For some reason we can't mint right now
+							continue;
+
 						newBlocks.add(newBlock);
 					} else {
 						// The blocks for other minters require less effort...
 						Block newBlock = newBlocks.get(0);
+						if (newBlock == null)
+							// For some reason we can't mint right now
+							continue;
+
 						newBlocks.add(newBlock.remint(mintingAccount));
 					}
 				}