[GNC] Since last run... errors

[Ronald Wiplinger]

I am using GNUcash for a few weeks and when I start the program a popup
window shows me some errors. I have no idea how to solve this.

I shows:
v  Alexander's contribution
    06/06/20                      To-Create
v  house rent
    09/04/20                      To-Create
        (null) -> TWD                   (Need Value)
....

The list goes on, always telling me:
        (null) -> TWD                   (Need Value)

I cannot find the transaction in any account.
I tried to add a value where it says Need Value. To find it easy later I
choose 99999 as value.

After I click OK I get another pop up, telling me:

Invalid Transactions
Unknown account for guide
[ab745cddc36 ... ], canceling SX
[Alexander's contribution] creation.
Unknown account for guide
[ab745cddc36... ] caneling SX [house rent] creation.
....

Needless to say, but next start of GNUcash gives me the same problem.

How to fix this?