Contract number: ECHA/2020/724  Restricted  Service contract conditions of December 2018  (b) has caused disruption at the premises of the contracting authority.  II.4.9  The contractor must record and report to the contracting authority any problem that  affects its ability to provide the services. The report must describe the problem, state  when it started and what action the contractor is taking to resolve it. II.4.10  The contractor must immediately inform the Contracting authority of any changes in the  exclusion situations as declared, according to Article 137 (1) of Regulation (EU)  2018/1046.  (a) be made in writing in paper or electronic format in the language of the contract; (b) bear the contract number;  (c) be made using the relevant communication details set out in Article I.8; and  (d) be sent by mail, email or, for the documents specified in the special conditions, via  e- PRIOR . The contractor bears the cost of replacing its  personnel  and is responsible for any delay  in providing the services resulting from the replacement of  personnel .  Any communication of information, notices or documents under the contract must:  If a party requests written confirmation of an e-mail within a reasonable time, the other party  must provide an original signed paper version of the communication as soon as possible.  The parties agree that any communication made by email has full legal effect and is admissible  as evidence in judicial proceedings.  Any communication is deemed to have been made when the receiving party receives it, unless  this contract refers to the date when the communication was sent.  E-mail is deemed to have been received by the receiving party on the day of dispatch of that e- mail, provided that it is sent to the e-mail address indicated in Article I.8. The sending party  must be able to prove the date of dispatch. In the event that the sending party receives a non- delivery report, it must make every effort to ensure that the other party actually receives the  communication by email or mail. In such a case, the sending party is not held in breach of its  obligation to send such communication within a specified deadline.  Mail sent to the contracting authority is deemed to have been received by the contracting  authority on the date on which the department responsible referred to in Article I.8 registers it.  Formal notifications  are considered to have been received by the receiving party on the date of  receipt indicated in the proof received by the sending party that the message was delivered to  the specified recipient. If provided for in the special conditions, the exchange of electronic documents (e-documents)  such as invoices between the parties is automated through the use of the  e-PRIOR  platform.  This platform provides two possibilities for such exchanges: either through web services  (machine-to-machine connection) or through a web application (the  supplier portal ). The contracting authority takes the necessary measures to implement and maintain electronic  systems that enable the  supplier portal  to be used effectively. 14  II.5.3 Submission of e-documents via e-PRIOR  II.5.2 Date of communications by mail and email  II.5.1 Form and means of communication II.5. COMMUNICATION BETWEEN THE PARTIES 