Need information to understand why api calls sometimes failed

Need information to understand why api calls sometimes failed

Hi Support,

From CRM workflow Rules I trigger a deluge function. Sometimes this function succeeds and sometimes it fails with the same params.

I need your help to understand what failed, I only received poor information like : 
- Error at line : 566, Error due to - '{0}'
- Error at line : 525, Execution exception : 'Error due to - 'Internal Exception''
- Error at line : 525, Error due to - '{0}'

Each error is linked to a call to Zoho project (to create a task or a subTask). I implemented sleep to decrease Zoho project limitations (100 call in 2 minutes).

In my deluge code I wrote a big try/catch to intercept these exceptions. Is it possible to get relevant information in the error object ? Currently I just print the error as a string.
EX :
try {
zohoSubTask = invokeurl
[
url : {validURL}
type :POST
parameters: {validBody}
connection:"zohoproject"
];
}catch (error)
{
      info "Error: " + error;
}

Could you help me ? Is there a screen where I can see all failed calls (in Zoho CRM or Zoho projects) ?

Regards,

Simon