As seen on the CARM Client Portal home page:
A fix has been implemented to address certain timeout errors related to Commercial Accounting Declarations (CAD), delegation requests or to request a report. However, the error message may still display when uploading a document in the CARM Client Portal (CCP).
In this case, please note that the document is likely uploaded despite the error. To confirm, click the Upload icon to view the list of uploaded documents. Please do not submit a ticket, as a permanent fix will be deployed shortly.

Please visit this link for more information: https://ccp-pcc.cbsa-asfc.cloud-nuage.canada.ca/en/homepage