The Barnsley Town Hall-based museum, forced to close in March due to coronavirus concerns, will now reopen on November 7.
Staff had grand plans for the weekend, having already delayed the reopening once this month - but concerns over safety caused by unforeseen issues forced the decision.
The archives will reopen as planned on Monday from 10am until noon, and then 2pm until 4pm.
Visitors to the archives will have to book in advance by emailing firstname.lastname@example.org.
A temporary exhibition space in an area unaffected by the work will open next month.
Coun Tim Cheetham, cabinet spokesperson for place, regeneration and culture, said: “Unfortunately due to emergency maintenance work the opening of Experience Barnsley Museum has been postponed.
“Although disappointing the safety of visitors is of utmost importance.
“The temporary exhibition space, which has not been affected by the work, will reopen with the launch of their latest exhibition ‘I Grew Up in the 80s’ on October 24. It will be a fun, light-hearted look back at the decade that brought us everything from Pac Man to iconic musical hits.
“The main galleries will reopen on November 7 with a wonderful new display of objects and artefacts telling the fascinating story of the borough.”