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E00007 / E_WC_21 User authentication failed

We have been testing with the SandBox for some time now.  All of a sudden (the beginning of Nov) we are now getting: E00007 – User authentication failed due to invalid authentication values.  There have been no code changes on our end.  

I double checked my LoginID and TransactionKey values, they are correct.  I double checked my AuthorizeNet.Environment value and it is SANDBOX.  I know I am calling the test URL, this is the http request header pulled from Fiddler:

Content-Type: text/xml
Content-Length: 898
Expect: 100-continue



Why am am I all of a sudden getting this error?  I have reviewed the blog and found others having similar problems that just magically started working again.

I could use some help with this. I am close to our release date and if I cannot trust the SandBox to be stable how can I trust the Production side to be as well?



Hi @Simple1Test,


This seems to be an intermittent issue . It has been observed that this is solved automatically. Observed that, for few people this issue was solved automatically. Please re-check merchant login Id and transaction key. 


You can check the endpoints and validity of the sandbox credentials using 'Test your Sandbox Credentials' at


Also please try to regenerate the transactionkey , sometimes it helps. Please refer the below link for this.


HTH, Thanks

Developer Developer