Hertsmere planners have dashed hopes that the Elstree and Borehamwood eruv would be operational in time for the summer.
The council's planning department has decreed that retrospective consent must be obtained for the relocation of some of the final pole positions.
Eruv organisers say the changes are primarily to deal with obstacles such as underground utilities, trees, roots and wire clearances, which could not have been anticipated in advance.
In a statement, the Ebor Eruv Trust said it had hoped the planners would nod through the changes. Instead, they had raised "possible legal concerns", requiring a retrospective application.
"This is regrettable as there are no planning issues, nor are any residents impacted by any of these changes."
However, Hertsmere's planning portfolio holder, Councillor Hannah David, maintained: "As a significant number of poles are in a different position to what was agreed, and these new positions are having an impact on local residents, we are legally obliged to ask the trust to submit a new planning application."
The council was working closely with the trust and the local community to resolve the issue speedily.
A Hertsmere spokesman added that some residents had complained that poles had been erected closer to their properties than had been anticipated.
The trustees aim to have the revised application ready within the next fortnight. The planning department must complete the review process, including consultation with residents, within an eight-week period, with the application considered at the next available planning committee meeting. It seems likely, therefore, that the eruv will not be in place until after the High Holy-Days - a delay which the trustees accept "will cause frustration" to many.
Local mother-of-three Efrat Arnold had been looking forward to the eruv's completion in time for summer get-togethers. "It is obviously upsetting that there has been another delay," she said. "I hope Hertsmere Council deal with the revised application quickly."