A group representing nightclub owners said the Scotland vaccine passport application was “not fit for purpose” and led to “chaos and confusion” on the first weekend of its implementation.
The program officially began in the early hours of Friday, although the application will not begin until October 18.
Clubs were asked to check the immunization status of clients prior to entry.
The NHS Scotland Covid Status app launched on Thursday, but technical issues have prevented many users from accessing their vaccine certification.
The government said the delay in applying means no one should be turned away from nightclub doors this weekend.
On Saturday, the Night Time Industries Association (NTIA) said sites across Scotland had reported “high levels of customer frustration with the government’s lack of information and the chaotic rollout of the app.”
He added: “It has become very clear that the Scottish app is simply not suitable for its purpose and the vast majority of people experience repeated problems recording and uploading their personal immunization status to the app.”
The industry body has opposed the introduction of the vaccine passport program, which the Scottish government says will encourage uptake of the vaccine.
Mike Grieve, president of NTIA Scotland and director of the Sub Club in Glasgow, said many customers were showing the wrong type of vaccine certification at the door.
He said: “As expected, the deployment of this ill-conceived policy led to chaos and confusion on the streets last night with only a handful of our clients in possession of a working enforcement passport.
“About 50 to 60 others had a photocopy or screenshot of incorrect vaccination information or other misleading vaccination evidence.
“Despite this, we successfully verified all participants for LFTs (lateral flow tests) on the same day to protect the health and safety of our customers and staff.
“What a mess.”
The NTIA approached the Court of Session to try to stop the vaccination passport program earlier in the week, but to no avail.
The Scottish Government said the first problems with the app were due to a high number of users trying to access data at the same time.
The government apologized and said the capacity of the NHS systems behind the app had been increased.
Health Secretary Humza Yousaf said on Friday that the problems should be resolved “if not in hours, at least in days.”
He told Bauer radio: “If you are planning on going out to a nightclub tonight or going to football on the weekends, go ahead anyway.
“Therefore, there is nothing in the regulations that means you should be turned away from the nightclub door or the turnstiles this weekend.”
A Scottish government spokeswoman said on Saturday: ‘We have had extensive discussions with stakeholders over the past month and have introduced the grace period in response to their comments to allow the system to be tested.
“We have also provided detailed advice for the sites and the public that we will keep informed. “
She continued: “There are no plans to delay the entry into force of the implementing provisions.
“A total of 167,600 people have now downloaded the application since its launch.
“We are aware of some start-up issues which are mainly due to the volume of requests, the work that has already taken place has solved many of the problems that people have encountered.
“We expect all remaining issues to be resolved shortly.”