The special educational needs (SEND) system in Bristol is "not fit for purpose and disturbingly poor", a report has said.
The joint Ofsted/CQC report said parents are "overwhelmingly condemning" of the way the council supports SEND children and young people.
Inspectors highlighted "significant leadership weakness" and "extensive delays" in education care plans (EHCP).
The council "apologised unreservedly" to families who "feel badly let down".
The inspection took place between 30 September and 4 October and the report concluded a Written Statement of Action would be required due to "significant areas of weakness in the local authority's practice".
Main findings from the report included the "dysfunctional and inadequate" process and quality of the EHCPs. Parents told inspectors they were "not worth reading".
The report noted there had been "noticeable improvements" in the leadership of SEND since 2018 and local authority leaders were "honest about the significant weaknesses" in the system.
But inspectors said there was a "significant amount of catching up to do that is needed urgently".
Jen Smith from Bristol Independent SEND Community, who has two autistic children, said the report's findings "did not come as a surprise to us" and show "the reality was known and allowed to continue unchecked".
"It costs time and money to force a lawfully-written EHCP out of Bristol.
"Parents and carers who lack the financial capital, the social peer support, or do not have English as a first language are all at greater disadvantage and struggle to obtain the services and education that is their children's legal right.
"SEND should not be an afterthought, a nice thing to have, a golden ticket. It's an integral part of education and protected in law.
"No more excuses and no more apologies. We want action now."
Bristol City Council's Director for Education and Skills Alison Hurley said: "One key area where people have been let down is the waiting time for EHCPs.
"We have addressed the staff shortages that have caused this by recruiting 24 new staff to work specifically on EHCPs, for example.
"We will be better able to cope with demand and improve timeliness, but it will take time for these improvements to be felt by the parents and carers of children and young people with SEND in Bristol."