There are very few Banach spaces \(E\) for which the lattice of closed ideals in the Banach algebra \(B(E)\) of all continuous linear operators on \(E\) is fully understood (up to the paper under review, the only such spaces were Hilbert spaces and the sequence spaces \(c_0\) and \(\ell_p\) with \(1\leq p< \infty\)). Now the authors add a new space to this family. More precisely, it is shown that for the Banach space \(E\) given by the \(c_0\)-sum of the finite-dimensional Hilbert spaces \(\ell_2^1,\dots,\ell_2^n,\dots\), there are precisely two non-trivial closed ideals, namely the ideal of compact operators and the closure of the ideal of operators that factor through \(c_0\). The erratum corrects a number of typographical errors, especially in the proof of Theorem 4.4 (p. 120).