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In the transaction /IQX/OL_ENDPOINT there is a 'Connection Test' option to check for the correctness of the URL and API key. This can be executed in each system:
or, for example, 
| Note |
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When generating and saving API keys for S4 Hana systems, please note that if the API key starts with special characters (e.g., exclamation mark "!"), the API key value |
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may not be saved. This |
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is a limitation of the password field used to mask the confidential API key in some versions of the SAP GUI. |
OneList Integration configuration
Note that you will (only once) have to configure a User integration entry. You may end up with multiple processes integrating with OneList, each of which will require their own entry here (and follow-on entries - see below). It does not matter how many processes you integrate with OneList, you will only need to do this step once - the processes all share the user integration. Add an entry to synchronise the SAP users with OneList, as follows (and note that the Task ID and the Fab Layout form entries remain empty):
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