Personal gateway - InvalidCredentialFormat - Signature does not match

I have a dataset which uses the personal gateway to publish data. I have used it succesfully for more than 3 months.

Last succesfull data refresh was 29/3. When I tried to refresh the data 2/4 it says in the error message that the gateway is not online. Even though it is.

I have tried to uninstall and reinstall the data gaway (march 2018 version).

The gateway logs report an error, that I don't know what to do with (see below).

Any suggestions would be appreciated.

****

GatewayPipelineErrorCode=DM_GWPipeline_Gateway_SignatureNotMatchCredentialError --->
Inner exception chain: System.FormatException
<pi>System.FormatException: InvalidCredentialFormat - Signature does not match
ved Microsoft.PowerBI.DataMovement.CommonUtilities.SymmetricKeyEncryptionHelper.Decrypt(SymmetricKeyEncryptedResultDataContract encryptedData, SymmetricKeyContractBase key)
ved Microsoft.PowerBI.DataMovement.Pipeline.GatewayDataAccess.CredentialUtils.DecryptSymmetricKey(SymmetricKeyEncryptedResultDataContract encryptedData, SymmetricKeyContractBase key)</pi>
--- End of inner exception stack trace ---
([0]Microsoft.PowerBI.DataMovement.Pipeline.Diagnostics.InvalidCredentialDueToSignatureNotMatchException.StackTrace:)
ved Microsoft.PowerBI.DataMovement.Pipeline.GatewayDataAccess.CredentialUtils.DecryptSymmetricKey(SymmetricKeyEncryptedResultDataContract encryptedData, SymmetricKeyContractBase key)
ved Microsoft.PowerBI.DataMovement.Pipeline.GatewayDataAccess.CredentialUtils.DecryptCredential(CredentialDetails credentialDetails, IGatewayCredentialStore credentialStore)
ved Microsoft.PowerBI.DataMovement.Pipeline.GatewayDataAccess.DbConnectionProviderBase.DecryptCredential(CredentialDetails credentialDetails)
ved Microsoft.PowerBI.DataMovement.Pipeline.GatewayDataAccess.MashupConnectionProviderBase.PrePrepareMashupCredential(DataSourceGatewayDetails datasource, String dataSourceKind)
ved Microsoft.PowerBI.DataMovement.Pipeline.GatewayDataAccess.MashupOleDbConnectionProvider.<PrepareMashupCredential>d__5.MoveNext()