Login problem with REST API in Enterprise environment /Portal

[NirmalOjha]

Hello,

For some time now, I have been unable to login using REST API nor I am able to generate token. It used to be working but now it is not working. No configuration has been changed. I used the following URL pattern for generating the token but I get response as invalid username or password:

https://webadaptor.domain.com/arcgis/sharing/rest/generateToken 

Response:

{"error": {  "code": 400,  "message": "Unable to generate token.",  "details": [   "Invalid username or password.",   "Invalid username or password."  ] }}

The only user account that works with the above URL and REST API is the default admin account, any other account results in 
Invalid username or password.
I can login to the portal fine with the browser https://webadaptor.domain.com/arcgis and it allows me to login using enterprise login.

Thanks.

Nirmal

[NirmalOjha]

Thanks a lot. Your comment helped me identify the issue. It was related to the service account but indirectly. I have to use the portaladmin/security/config and updated the identity store. The password of service account was changed. Everything else were working and I had used the config tool in the portal directory to update the info as well.

Nirmal

[ZachBodenner]

Sorry for reviving a kind of old thread, but I'm having a similar issue, only my service account password has not changed, and I am only having trouble generating tokens from virtual and off-network machines, which is important for some third party software. Any ideas of other possible causes?