The Eagles on Tuesday confirmed that Dougie Freedman, a popular figure as both player and manager, had left the club to take charge of Championship rivals Bolton, with assistant Lennie Lawrence and first-team coach Curtis Fleming in control of Palace on Tuesday night.
They saw their side extend their excellent unbeaten run to nine matches, although Glenn Murray's early strike was cancelled out by Perkins' wonderful late leveller.
It was a suitably cruel way for the day to end for Palace, although they had come firing out of the traps and Murray should have done better when he fired over with a first-time shot from Yannick Bolasie's left-wing cross.
The 27-year-old would make no mistake with a similar opportunity, however, as the visitors gave their few hundred fans, who had made the long trip up to Yorkshire, something to cheer about.
Jonathan Parr was allowed to maraud down the left flank and pick out Murray to slot past Ben Alnwick in the 11th minute.
Barnsley's goalkeeper had to be at his best to claw away Murray's back-post header from an Owen Garvan corner soon after.
After such a frenetic opening it was unsurprising to see Tykes boss Keith Hill bolster his midfield by replacing forward Chris Dagnall with Matt Done after 17 minutes.
The change seemed to pay dividends for Barnsley, who saw Marlon Harewood's effort blocked excellently by Damien Delaney while Done forced Palace goalkeeper Julian Speroni to make an excellent save with a powerfully struck effort from the edge of the area.
Delaney was again on hand to stop the former Nottingham Forest and Newcastle striker from latching onto Scott Golbourne's inviting cross as Barnsley started to gain the upper hand.
Palace, who let slip a two-goal lead in their 2-2 draw with London rivals Millwall at the weekend, defended stoutly into half-time and it seemed Barnsley were badly missing the presence of eight-goal top-scorer Craig Davies, absent with a hamstring injury.
The pattern continued into the second half, with Speroni largely a spectator and Barnsley desperately lacking a cutting edge in the final third.
The lack of creativity nearly cost them as Palace broke, and although Andre Moritz had the opportunity to play Murray through he chose to go it alone and was taken out by Stephen Foster, who received a yellow card.
That seemed, temporarily at least, to rouse the crowd and Danny Rose, introduced to add some fresh legs up front, fired over after being teed up by Harewood.
However, the hosts were grateful when Kagisho Dikgacoi's cross-cum-shot cannoned to safety off the inside of the right post after looping over Alnwick.
And they made full use of their let-off as Perkins levelled matters four minutes from time.
The midfielder picked up a loose ball on the edge of the area before curling marvellously into the top corner with Speroni well beaten.
