What to do if I have mistakenly filled wrong passing year in e dossier of DSSSB

After searching for the correction in the filled-in upload in the e-dossier of the Delhi Subordinate Services Selection Board(DSSSB), not much has been found to give you but as per the received information, one can register their complaint in the complaint board or the National Consumer Complaint Forum. You can raise a separate complaint in the forum (https://www.complaintboard.in/complaints-reviews/dsssb-l380126.html) with other details like:
Subject: Correction in my passing date/year of class XXXX.
Name-
Reg no.-
Application no.-
Post -
Post code -
Mobile no-
Email-id -

Many applicants have such complaints and query and one can get solutions from the portal. You can even keep a screenshot to print of the registered complaint about your safety as you can show them when called or intimated about the correction.

Though we need to furnish the details correctly while feeling up an application form for any post irrespective of the mode selected for the same. One should ensure the correctness of the details furnished in your application in case of off line method addressed to the appropriate authority. In case of detection of the mistake, one has to intimate the same to the authorities concerned in time so that they entertain your grievances.
Write a letter to the the authorities indicating the wrong entry of year of passing giving the correct details of year of passing. Mention the application number and date when you dispatched the application form in a registered post with the acknowledgment of certificate of posting to be reached to you ultimately once they receive the same.
If the same has been sent through online mode, give the entire details earlier filled apart from the new enclosure of your year of passing requesting them for the correction at the earliest.

https://dsssb.delhi.gov.in/ is the original website of the Delhi Subordinate Services Selection Board(DSSSB). https://dsssbonline.nic.in/ is the site one will use for registering their candidature for a post against their advertisements.

The contact address as per the site is
The Controller of examinations,
Delhi Subordinate Services Selection Board (DSSSB)
FC-18, Institutional Area, Karkardooma , DELHI-110092 Phone:+91-011-22370309

I suggest you contact them on phone and inform them of the mistake you have committed while submitting the application and ask them the way forward. If there is no response from them you can make an application to the above address stating the mistake and mentioning the correct date of birth. To this application, you can attach a copy of the certificate showing your correct date of birth. Then send this application to them by registered post with an acknowledgement due. Keep a copy of your letter with an attachment for your reference and you can show it when they call for an interview.

Generally, they will not disqualify your application for this post and they will give a chance for you to correct it by a separate submission.

You can try to contact telephonically the controller of the examination and request him about the correction of the mistake as you are not able to do that in the site as post editing facilities are generally not available in these matters. Another thing is that send an email and as well as send a physical letter to their address and make a request for that correction. Please keep all the copies of the correspondences made by you to confirm the same at a later time when they ask about that and seek documentary evidence to what you claim.

In most cases, instructions are given in advance to be careful while filling any form, but still, sometimes such mistakes can happen, then one can also apply for correction till the date. Since the time has become more in your case, for this,

You can either go to the concerned website and see its details, in which you will get the complete process related to it,
Or you can drop an email on the email id given on the website
Or make a call to reception/contact numbers that are already given on the website
Or give this information to the concerned officers by letter in the appropriate department.

Do not worry too much just follow all possible options and hope for the best.