I have Homework1 of week 5, and it works in the repl (meaning, the test gives the expected result). However, when I try the script in the playground (and remove the test - I don't think that makes a big difference, though, and I removed the line module ...), it's stuck on slot 1, at the bottom:

("txSignatures",Array []),("txValidRange",Object (fromList [("ivFrom",Array [Object (fromList [("tag",String "NegInf")]),Bool True]),("ivTo",Array [Object (fromList [("tag",String "PosInf")]),Bool True])]))])),("unBalancedTxUtxoIndex",Array []),("unBalancedTxValidityTimeRange",Object (fromList [("ivFrom",Array [Object (fromList [("tag",String "NegInf")]),Bool True]),("ivTo",Array [Object (fromList [("contents",Number 1.596059152999e12),("tag",String "Finite")]),Bool True])]))]))])),("mkTxLogTxConstraints",Object (fromList [("txConstraints",Array [Object (fromList [("contents",Array [String "aea02b83a8e055c06b768c2fcbf1101422b78405892b5027144ddb3b",String "d87980",Object (fromList [("unTokenName",String "ABC")]),Number 5.0]),("tag",String "MustMintValue")]),Object (fromList [("contents",Object (fromList [("ivFrom",Array [Object (fromList [("tag",String "NegInf")]),Bool True]),("ivTo",Array [Object (fromList [("contents",Number 1.596059152999e12),("tag",String "Finite")]),Bool True])])),("tag",String "MustValidateIn")])]),("txOwnInputs",Array []),("txOwnOutputs",Array [])]))])
, Slot 1: 00000000-0000-4000-8000-000000000000 {Wallet W872c}:
            Handled request:   Iteration 3 request ID 1
                               Response: "{\"contents\":1596059092999,\"tag\":\"CurrentTime
, Slot 1: 00000000-0000-4000-8000-000000000000 {Wallet W872c}:
            Current requests (1):   Iteration 4 request ID 1
                                    Request: "{\"contents\":{\"unBalancedTxRequiredSignatories\
, Slot 1: 00000000-0000-4000-8000-000000000000 {Wallet W872c}:
            Handled request:   Iteration 4 request ID 1
                               Response: "{\"contents\":{\"contents\":{\"contents\":{\"cont
, Slot 1: 00000000-0000-4000-8000-000000000000 {Wallet W872c}:
            Current requests (0): 
, Slot 1: 00000000-0000-4000-8000-000000000000 {Wallet W872c}:
            Contract instance stopped with error: "WalletError (ValidationError (ScriptFailure (EvaluationError [\"PT5\"] \"CekEvaluationFailure\")))" ]

I don't really understand why the script fails in the playground, while it works perfectly fine in the repl. How to try out the same script in the repl?


== EDIT 15/02/2022

The code: https://gitlab.com/moment-4/courses/plutus-pioneer/plutus-pioneer-program/-/blob/week05/code/week05/src/Week05/Homework1.hs

The important lines (I think):

mkPolicy :: PaymentPubKeyHash -> POSIXTime -> () -> ScriptContext -> Bool
mkPolicy pkh deadline () ctx = 
   txSignedBy txInfo (unPaymentPubKeyHash pkh) &&
      to deadline `contains` txInfoValidRange txInfo
         where txInfo :: TxInfo
               txInfo = scriptContextTxInfo ctx

policy :: PaymentPubKeyHash -> POSIXTime -> Scripts.MintingPolicy
policy pkh deadline = mkMintingPolicyScript $
   $$(PlutusTx.compile [|| mintingPolicyScript ||])
   PlutusTx.liftCode pkh
   PlutusTx.liftCode deadline
         mintingPolicyScript :: PaymentPubKeyHash -> POSIXTime -> Scripts.WrappedMintingPolicyType
         mintingPolicyScript = \pkh' deadline' -> Scripts.wrapMintingPolicy $ mkPolicy pkh' deadline' 

curSymbol :: PaymentPubKeyHash -> POSIXTime -> CurrencySymbol
curSymbol = \pkh' deadline' -> scriptCurrencySymbol (policy pkh' deadline')
  • Can you share your code?
    – kindofdev
    Feb 14, 2022 at 19:23
  • yes, sure, see edit in my description. Thx.
    – Kurt Sys
    Feb 15, 2022 at 16:58

1 Answer 1


I've reproduced exactly the same scenario in the tests (homework 1) over the playground with your code and it works as expected: first attempt mints and second one fails because deadline. Most probably the issue is related to your input. (deadline is posixtime, not slots)

enter image description here

deadline = 1596059191000 . I got it doing in the repl:

import Ledger.TimeSlot
import Data.Default 
slotToBeginPOSIXTime def 100  -- slot 100

enter image description here


After reading your comment the issue comes from this line in offchain code:

Constraints.mustValidateIn (to $ now + 60000)

because the tx doesn't pass the validRange pre-validation phase. If you play using a lower value you'll this in action.

As a side note, this is not a playground thing. You can test with Emulator Trace and won't be able to mint (probably with a different error message).

Hope this is useful.

  • Thx. When I use 100 slots (converted to POSIXTime), it works fine. When I use only 10 slots, it fails. So it seems the first transaction fails depending on the deadline. After bisecting, it seems that it only works if the deadline > POSIXTime of slot 61 (1596059152000) . Any idea why? Can it be because the deadline is already passed (time for compilation etc, but in that case, ~60 slots seems a lot)?
    – Kurt Sys
    Feb 15, 2022 at 20:11
  • Do you mean 10 slots as deadline?
    – kindofdev
    Feb 15, 2022 at 20:16
  • yes, exactly. 10 slots (converted to POSIXTime) - it only works if it's >61 slots (on my laptop), converted to POSIXTime
    – Kurt Sys
    Feb 15, 2022 at 20:23
  • Yeah, that's it, thanks - and yes, extremely useful!! I forgot about that weird now + 60000. That was kind of a hacky solution to get it right - and hacky solutions result often in unexpected results. Anyway, it all makes perfect sense now, great.
    – Kurt Sys
    Feb 16, 2022 at 7:30

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