429 too many requests

We are experiencing some outages with the APIs, out from 10 conversions from word to PDF 8 get converted successfully and 2 failed.

We found a repetative error in the log: "Too Many Requests" (HTTP 429) :

09:57:20.520 [ajp-nio-0:0:0:0:0:0:0:0-8019-exec-5] INFO  c.a.p.o.internal.PDFServicesHelper:188 - Started submitting Document Merge Operation job 

09:57:20.520 [ajp-nio-0:0:0:0:0:0:0:0-8019-exec-5] DEBUG c.a.p.o.internal.PDFServicesHelper:189 - Submitting Document Merge Operation job with request id 283b2ad4-6def-4164-b8d2-8af4836515ae 

09:57:20.521 [ajp-nio-0:0:0:0:0:0:0:0-8019-exec-5] INFO  c.a.p.o.internal.PDFServicesHelper:204 - Finished submitting Document Merge Operation job 

09:57:20.521 [ajp-nio-0:0:0:0:0:0:0:0-8019-exec-5] DEBUG c.a.p.o.i.a.ServicePrincipalAuthenticator:63 - Session Token is valid, won't be refreshed. 

09:57:20.522 [ajp-nio-0:0:0:0:0:0:0:0-8019-exec-5] DEBUG c.a.p.o.internal.http.ApacheHttpUtil:47 - Creating Apache HTTP POST request for PLATFORM 

09:57:20.754 [ajp-nio-0:0:0:0:0:0:0:0-8019-exec-5] DEBUG c.a.p.o.internal.http.HttpClient:191 - Response received: 

HttpResponseProxy{HTTP/1.1 429 Too Many Requests [...]} 

09:57:20.757 [ajp-nio-0:0:0:0:0:0:0:0-8019-exec-5] ERROR c.a.p.o.internal.http.HttpClient:221 - Failure response code 429 encountered from backend 

Please advise.